Image processing for a game

ABSTRACT

This image processing device for games is a device whereby a prescribed number of models (characters) are setup in virtual space, these models are controlled such that they move in prescribed directions in the virtual space, and images of this virtual space from a virtual viewpoint are displayed on means for display. In order to display the movement of the models that are arranged in virtual space more realistically, in one construction thereof, this device is provided with means for image processing that apply virtual centripetal force to the models. Furthermore, in order to display the movement of the models more realistically and to heighten the dramatic effect, in one construction thereof, this device is equipped with means for processing residual image presentation in order to represent the track of movement of a model as residual images. This means for processing is equipped with means for storage that store without modification motion data of the model prior to the current motion and with means for display control that display this stored data together with the current motion data.

TECHNICAL FIELD

[0001] The present invention relates to the processing of images in avirtually set-up game space (hereinbelow called “virtual space”)(hereinbelow called “virtual images”); in particular, it relates toimage processing for a game whereby the movement of a virtual model thatis set up in virtual space (for example called a “character”) on ascreen can be represented more realistically. This image processingtechnique is suitable in particular for 3D video games machines.

BACKGROUND ART

[0002] Due to the development of computer graphics (CG) technologies, ithas become possible to represent a virtual space (also called “virtualworld”) that is set up in virtual fashion three-dimensionally and inrealtime. This is the technical field of video games machines: thesehave been developed in recent years and incorporate a central processingunit (CPU) capable of high speed computation and a video displayprocessor (VDP) and enable such computer graphics technologies to beutilised at high speed and in economical fashion.

[0003] In such a video games machine, the content of game play changescontinually depending on the actions of the user (also called the gameplayer or player), so the objects that are displayed have to be movedfreely at high speed in virtual space. To this end, usually a modelconstituting an object to be displayed (for example a character) isconstituted of a set of polygonal fragments called polygons oftriangular or quadrilateral shape, and the movement of such models isdisplayed by simultaneously altering the spatial position of thesepolygons.

[0004] Also, when specified portions or faces of objects to be displayedsuch as the arms or legs of characters were to be moved simultaneously,a polygon data group consisting of an assembly of a plurality ofpolygons was taken as a unit and a spatial position was given to eachpolygon data group, so that the specified portions or faces could bemoved simultaneously.

[0005] In recent years, so-called 3D (three-dimensional) games haveattracted attention in the market, in which a character is made up ofpolygons and an image is represented on a monitor in which the movementof the character in virtual space is captured from a virtual viewpoint;simulations of fights between a plurality of warriors are particularlypopular (for example, “Virtual Fighter” (trade mark) made by SegaEnterprises Limited). In such a fighting simulation game, a playerrapidly operates a stick or pad or button attached to a controller tomake a warrior represented on the screen perform actions in accordancewith commands determined by operation of the stick etc. The movements ofthe warrior are called “motion” and data in order to implement suchmotion is acquired using the “motion capture” technique. This data isthen processed, if need be, and is utilised as final motion data in a 3Dvideo games machine. In such a video game, in order to raise the productvalue, it is desirable to represent the movement of the character morerealistically. More specifically, this consists in for example addingmore varieties of movement whilst approaching very closely to theactions of an actual warrior. However, since the anticipated movementsof a character extend over a very wide range of possibilities, there aremany problems that still need improvement in order to achieve such anobjective. Of course, consideration has been given to for examplecompiling beforehand all the desired motion data and storing this inmemory and obtaining characteristic expressions in order to get suchmotion, but the problem is that a large amount of data is required forthis, which is impossible to process in real time.

[0006] A chief object of the present invention is therefore to providean image processing technique for games whereby the amount ofcalculation and/or the amount of data required for image processing canbe greatly reduced and whereby the movement of the character on thescreen can be expressed more in real time and more realistically.

[0007] First specific aspects of a problem that was experienced inconventional video games machines from the point of view of this objectare as follows.

[0008] A1. In a 3D video game, since the image on the two-dimensionalscreen from the virtual viewpoint is represented by performing aprojection conversion, it is difficult to move the warrior in the depthdirection of the screen (z direction of virtual space) i.e. in thedirection of the player's gaze, so no consideration at all was given toenabling a warrior to walk around other warriors. To improve suchmovement around the characters is therefore a first specific object ofthe present invention.

[0009] A2. With a conventional 3D video games machine, there was theproblem that, since the images were displayed from a virtual viewpoint,if a structure such as a wall was arranged in virtual space in aposition such as to screen the warrior, display was effected with thecharacter blocked out. Accordingly, a further specific object of thepresent invention is to effect display in which this situation that thecharacter is blocked out by a structure is improved.

[0010] A3. In a conventional video games machine, the method was adoptedof generating the motion of the character sequentially using for examplea spline function, or the method of effecting reproduction ofpredetermined patterns in sequential frames. However, with theconventional video games machine, this motion was fixed, so it was notpossible to correct the motion to match the movement of a character onthe other side etc. Accordingly, a further specific object of thepresent invention is to enable such motion correction to be performed.

[0011] Further, as a derivation from the viewpoint of the above chiefobject, in addition to the first aspects described above, it is desiredto perform screen display with improved dramatic effect such ascharacter movement, in order to raise product value. Second aspects ofthe problems of conventional video games machines when this demand istaken into consideration may be described specifically as follows.

[0012] B1. “Motion blur” is known as a technique for improving thedramatic effect of a CG image. By means of such motion blur, a largenumber of rays are generated at a single pixel, and coloration isapplied wherein these are averaged, thereby enabling a picture to becreated that shows “out-of focus” or movement.

[0013] Furthermore, in recent years, in the field of CG video such asvideo games, in order to raise the dramatic effect further, in movementof a character, display is effected together with residual images suchas are liable to be produced physiologically in human visual perception.For example, residual images may be attached to the track of a swordthat is being waved by a warrior. Persons skilled in the art wouldtherefore calculate polygons and to constitute residual images matchingthe motion of the warrior and display these residual images in thevicinity of the warrior.

[0014] However, the anticipated movements of characters are extremelydiverse, so compiling polygons for a large number of modes of residualimages matching all these cases and storing these in memory restrictsthe performance of a limited computer graphics device and furthermorecalculation of residual-image polygons in conformity with the motion ofthe character puts a large load on the computer graphics device.Accordingly, in the formation of a CG image, yet a further specificobject of the present invention is to make it possible to displayresidual images simultaneously with the actual image screen withoutlarge increase in calculation load (or more precisely, reducing theload), even though measures are taken to raise the dramatic effect.

[0015] B2. In a games device using a conventional image processingdevice, flying material such as sand or water splashes is displayed onthe screen (for example “Sega Rally” (trade mark) manufactured by SegaEnterprises Limited) However, since such water splashes or sandscattering consisted merely in mapping texture on to polygons, it wasnot possible to reflect accurately the movement of the model (car etc.)by the flying material. Yet a further specific object of the presentinvention is therefore to reflect the movement of the model moreaccurately in the flying material.

[0016] B3. The quality of the conventional image processing device wasinsufficient in simulation of movement of a model falling in virtualspace. Yet a further specific object of the present invention istherefore to raise the quality of simulation of movement of free-fallthrough virtual space.

[0017] B4. In a conventional image processing device, the proximity of azone in virtual space and a moving model were determined and if thisdetermination was positive, movement of the model was restricted such asnot to go beyond the zone. Usually, as zones of this type, fixed-shape,for example quadrilateral or circular, type zones were setup. In thiscase, since the zone was of a typical shape, it was easy to calculatemovement that would expel the character from the zone. However, whenthis zone was irregularly shaped, there was the problem that it wasdifficult to cope with this situation with the conventional computergraphics device. Accordingly, yet a further specific object of thepresent invention is to enable the calculation processing of themovement (motion) of a model after there has been a positivedetermination of collision between the zone and the model to be executedaccurately and easily.

[0018] B5. Conventionally, in the field of image processing applied ingames devices, when a series of periodic pictures (for example, apicture of repeating waves or skipping etc.) was to be reproduced, aseries of such pictures was compiled by a manual operation to produce atexture series and a series of images in which the same action wasrepeated were represented by repeated sequential mapping of these on toa polygon.

[0019] Since the compilation of such texture series requires a lot ofmanual work, attempts have been made to utilise application software. Aknown example of such application software is called by the trade name:Alias/Wavefront (manufactured by Alias/Wavefront Inc. (110 RichmondStreet, East Toronto, Ontario, Canada, M5c 1p1). When such software isemployed, the target texture series can be obtained by supplyingprescribed parameters to the software.

[0020] However, when prior art software of this type is employed,pictures in which the starting and ending of the texture series i.e. thetexture pattern (mode) are not continuous for the player often result.

[0021] There was therefore room for improvement in the creation ofrepeating pictures in the field of conventional image processing. It istherefore yet a further specific object of the present invention toenable the compilation of a texture series of this type by imageprocessing.

[0022] B6. In a prior art image processing device, there were scenes inwhich, in order to improve the dramatic effect of the reproduced image,slow reproduction was performed in which the reproduction speed ofcharacter action was slowed down. However, the benefits of suchslow-reproduction performance were limited. Yet a further specificobject of the present invention is therefore to provide means for imageprocessing for games whereby the speed of reproduction can be varied inorder to create a better dramatic effect.

DISCLOSURE OF THE INVENTION

[0023] A chief object of the present invention is that there areprovided from various viewpoints techniques for the processing of imagesfor games whereby movement of characters on a screen can be representedin more real-time fashion and more realistically by greatly reducing theamount of computation and/or amount of data required for the imageprocessing. In the present invention, various constructions given beloware adopted in order to achieve various specific objects derived fromthis main object. A series of constructions constituting a first aspectof the present invention are as follows. Specifically, according to thepresent invention, there is provided an image processing device forgames wherein a prescribed number of models are set up in virtual spaceand these models are controlled such that they move in prescribeddirections in the virtual space and images of this virtual space fromthe virtual viewpoint are displayed by means for display, comprisingmeans for image processing whereby virtual centripetal force is appliedto the models. There is also provided a games device equipped with thisimage processing device for games. Furthermore, there is provided arecording medium on which is recorded information containing a series ofprocedures for implementing this means for image processing.

[0024] Furthermore, according to the present invention, an imageprocessing device of this type for games comprises means for imageprocessing whereby the amount of frictional force that is applied tothese models is varied when the models are moving and when they arestationary.

[0025] Furthermore, according to the present invention, an imageprocessing device of this type for games comprises means for imageprocessing whereby a projection image of the models is displayedmatching the surface shape of a stage on which the models are placed.Further, according to the invention, an image processing device of thistype for games comprises means for image processing whereby adetermination is performed of overlap of the field of view created bythe virtual viewpoint with respect to the model which is the subject ofdisplay and another model which is not set as the subject of display,and, if the result of this determination is affirmative, the other modelis not displayed.

[0026] Further according to the present invention, there is provided animage processing device of this type for games comprising means forimage processing whereby, with respect to the end-point of apredetermined movement track of the model, a target point is set updifferent from this end point and the movement track is interpolatedsuch that the end point coincides with this target point.

[0027] Further according to the present invention, there is provided animage processing device of this type for games comprising means forimage processing whereby a difference of level at which the model ispositioned in the virtual space is found and the action which is appliedto this model is interpolated in accordance with this level difference.

[0028] By means of such constructions, the movement of the model such asa character that is arranged in virtual space can be displayed morerealistically. Specifically, images whereby one model moves aroundanother model can be easily generated. Furthermore, the condition of thestage on which the model is placed can be reflected in the movement ofthe model. Furthermore, unevenness of the stage can be reflectedaccurately and in a simple manner in the projection image of the model.Furthermore, even if a structural object is a wall arranged in virtualspace at a position which would screen the model, display can beeffected without the model being screened. Also, versatile movement ofthe model can be represented in a reliable manner since it is possibleto correct motion of the model by matching it to movement etc. of theother model. Furthermore, more realistic images can be generated sinceit is possible to take into account level differences between models.

[0029] Also, a series of constructions that constitute a further aspectof the present invention is disclosed below. As one specificconstruction thereof, according to the present invention there isprovided an image processing device for games wherein a prescribednumber of models are set up in virtual space and these models arecontrolled such that they move in prescribed directions in the virtualspace and images of this virtual space from a viewpoint of prescribedposition are displayed by means for display; comprising means forresidual image representation processing for representing the track ofmovement of a model as residual images; this means for processingcomprising means for storage whereby motion data of the model before thecurrent motion are stored without modification and means for displaycontrol whereby this stored data is displayed together with currentmotion data of the model. This means for display control may comprisemeans for dramatic effects for effecting display with addition ofdramatic effects to the data of the means for storage. This means fordramatic effects may perform semi-transparent image processing.

[0030] As a further specific construction, according to the presentinvention, there is provided an image processing device for gameswherein a prescribed number of models are set up in virtual space andthese models are controlled such that they move in prescribed directionsin the virtual space and images of this virtual space from a viewpointat a prescribed position are displayed by means for display; comprisingmeans for dramatic effects that apply dramatic effects to the movementcharacteristic of the model and means for controlling flying materialthat cause flying material to be present in the virtual space and thatcontrol the series of movements of this flying material in accordancewith the results of the calculation by the means for calculation. As afurther specific construction, according to the present invention, thereis provided an image processing device for games wherein freefallmovement of a model set in virtual space is simulated and comprisingfirst means for simulating overall movement of the model and secondmeans for conferring a circulating movement on the model.

[0031] Further, as another specific construction, according to thepresent invention, there is provided an image processing device forgames wherein a prescribed number of models are set up in virtual spaceand these models are controlled such that they move in prescribeddirections in the virtual space and images of this virtual space from aviewpoint at a prescribed position are displayed by means for display;comprising means for setting up a zone that set up an irregularly shapedzone in the virtual space; means for setting up a vector consisting ofmeans for setting up a prescribed vector between this zone and thismodel and that, if this model tries to move beyond this zone, sets upthis vector in a direction such that the model does not go beyond thezone; and means for controlling model movement that control the movementof the model in accordance with this vector.

[0032] Furthermore, as a further specific construction, according to thepresent invention, in a device in which texture is formed that varies inperiodic fashion on application of a prescribed parameter, there areprovided first means for creating a first texture series and means forcreating a second texture series and a texture series is formed whereinparameters are applied to the respective means such that the first orlast texture of the first texture series and the first or last textureof the second texture series are constituted in continuous mode and thedegree of transparency of at least one of the first texture series andsecond texture series is gradually increased or decreased with theobject that superposition is effected in order from the first texturesof both texture series.

[0033] Also, according to the present invention, in a method of formingtexture series wherein periodically changing textures are formed, thereare provided a first step of creating a first texture series whichchanges in a prescribed direction and a step of creating a secondtexture series that likewise changes in a prescribed direction andwherein the last or first texture of the first texture series and thefirst or last texture of the second texture series are made to beconstituted in continuous mode and the degree of transparency of atleast one of the first texture series and second texture series isgradually increased or gradually decreased with the object thatsuperposition is effected in order from the first textures of bothtexture series.

[0034] Further, as a further specific construction, according to thepresent invention, there is provided an image processing device forgames wherein a prescribed number of models are set up in virtual spaceand these models are controlled such that they move in prescribeddirections in the virtual space and images of this virtual space from aviewpoint in prescribed position are displayed by means for display;comprising first means that determines whether or not a prescribedcondition is established between two models; second means for reflectingthe establishment of the condition in the movement of the respectivemodels and third means for, if this condition is established, changingthe reproduction speed of movement of one model with respect to theother model.

[0035] By means of such constructions, the movement of models in virtualspace can be represented more realistically and games images that arerich in dramatic effects can be generated. In more detail, with onespecific construction, there can be provided an image processing devicefor games in which large calculating load is not applied even thoughmeasures are taken to improve the dramatic effects in forming gameimages. Also, with another specific construction, there can be providedan image processing device for games whereby, even though such load issmall, residual images can be displayed simultaneously with the realimage screen. Furthermore, according to a further specific construction,there can be provided an image processing device for games whereinmovement of a model can be accurately reflected in flying material.Further, with a further specific construction, there can be provided animage processing device for games whereby simulation of higher qualityof freefall movement in virtual space can be achieved. Further,according to a further specific construction, there can be provided animage processing device for games whereby calculation processing ofmovement (motion) of a model after an affirmative determination ofcollision between a zone and a model can be executed easily and reliablyeven for the case of an irregularly shaped zone. Further, according to afurther specific construction, a series of texture series can be createdwhereby continuous images can be represented without a feeling ofincompatibility even though display is repeated and image processing isemployed. Yet further, with a further specific construction, there canbe provided an image processing device for games in which the speed ofreproduction can be varied to create a better dramatic effect.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036]FIG. 1 is a block diagram of a video games machine constituting animage processing device according to an embodiment of the presentinvention;

[0037]FIG. 2 is a flow chart showing the main processing in a firstembodiment;

[0038]FIG. 3 is a perspective view showing circular movement of acharacter in circular movement processing;

[0039]FIG. 4 is a detailed flow chart of circular movement processing;

[0040]FIG. 5 is a diagram illustrating circular movement in virtualspace;

[0041]FIG. 6 is a perspective view corresponding to a condition ofcompletion of circular movement;

[0042]FIG. 7 is a diagram of the principles of virtual frictionalprocessing;

[0043]FIG. 8 is a detailed flow chart of virtual frictional processing;

[0044]FIG. 9 is a diagram of the principles of projection displayprocessing;

[0045]FIG. 10 is a diagram of the principles of intersectiondetermination processing;

[0046]FIG. 11 is a detailed flow chart of intersection determinationprocessing;

[0047]FIG. 12 is a xz plane view of a structural object approximated byan inscribed circle;

[0048]FIG. 13 is a diagram illustrating the principles of a specificexample of intersection determination processing;

[0049]FIG. 14 is a diagram illustrating the principles of anotherspecific example of intersection determination processing;

[0050]FIG. 15 is a diagram illustrating the principles of a mode ofapproximating a structural object shaped as a wall;

[0051]FIG. 16 is a perspective view illustrating a standard mode ofcharacter motion;

[0052]FIG. 17 is a perspective view illustrating an interpolated mode ofcharacter motion;

[0053]FIG. 18 is a conceptual diagram illustrating the track of movementof a character produced using a spline function;

[0054]FIG. 19 is a flow chart illustrating an operation for charactermotion processing control;

[0055]FIG. 20 is a diagram illustrating a condition in which there is alevel difference between two characters;

[0056]FIG. 21 is a flow chart illustrating processing of character leveldifference;

[0057]FIG. 22 is a flow chart given in explanation of time flow of suchprocessing;

[0058]FIG. 23 is a diagram illustrating a condition in which leveldifference processing has been performed;

[0059]FIG. 24 is a photograph illustrating a front view of an example ofa human-like character;

[0060]FIG. 25 is a photograph showing a second example thereof;

[0061]FIG. 26 is a front view of a control pad to a larger scale;

[0062]FIG. 27 is a diagram illustrating file structure for a combiningtechnique;

[0063]FIG. 28 is a flow chart for the deployment of the combiningtechnique;

[0064]FIG. 29 is a screen front view illustrating a screen displayed bya combining technique processing step;

[0065]FIG. 30 is a front view displaying another screen displayed bythis processing step;

[0066]FIG. 31 is a front view displaying another screen displayed bythis processing step;

[0067]FIG. 32 is a front view displaying another screen displayed bythis processing step;

[0068]FIG. 33 is a front view displaying another screen displayed bythis processing step;

[0069]FIG. 34 is a flow chart illustrating main processing in a secondembodiment;

[0070]FIG. 35 is a front view of a model in respect of which residualimage processing has been performed;

[0071]FIG. 36 is a diagram showing the principles of residual imageprocessing;

[0072]FIG. 37 is a diagrammatic flow chart of residual image processing;

[0073]FIG. 38 is a detailed flow chart thereof;

[0074]FIG. 39 is a detailed flow chart of the flow chart of FIG. 37;

[0075]FIG. 40 is a diagram showing the track of flying material that hasbeen churned up;

[0076]FIG. 41 is a diagram given in explanation of the occurrence oflanding of flying material;

[0077]FIG. 42 is a view given in explanation of the occurrence oflanding of flying material;

[0078]FIG. 43 is a view given in explanation of the occurrence oflanding of flying material;

[0079]FIG. 44 is a view given in explanation of the occurrence oflanding of flying material;

[0080]FIG. 45 is a view given in explanation of the occurrence ofchurning-up;

[0081]FIG. 46 is a vector line diagram on the occurrence of churning-up;

[0082]FIG. 47 is a vector line diagram on the occurrence of churning-up;

[0083]FIG. 48 is a flow chart of flying material movement processing;

[0084]FIG. 49 is a rear view of a character to which flying materialmovement processing has been applied;

[0085]FIG. 50 is a diagrammatic flow chart of such processing;

[0086]FIG. 51 is a detailed flow chart thereof;

[0087]FIG. 52 is a detailed flow chart thereof;

[0088]FIG. 53 is a detailed flow chart thereof;

[0089]FIG. 54 is a view illustrating a mode of movement of flyingmaterial;

[0090]FIG. 55 is a view illustrating a mode of movement of flyingmaterial;

[0091]FIG. 56 is a view illustrating the movement track of an object inrespect of which free-fall movement processing has been performed;

[0092]FIG. 57 is a diagram illustrating the principles of collisiondetermination processing of an irregularly shaped zone and a model;

[0093]FIG. 58 is a flow chart thereof;

[0094]FIG. 59 is a diagram illustrating the principles of compilation ofa texture sequence;

[0095]FIG. 60 is a front view illustrating a condition in whichchurning-up and landing occurrence of flying material have been producedby a model;

[0096]FIG. 61 is a side view given in explanation of character operationfor explaining the principles of slow reproduction processing;

[0097]FIG. 62 is a plan view seen from above of FIG. 61;

[0098]FIG. 63 is a side view given in explanation of character action inthe slow reproduction condition;

[0099]FIG. 64 is a plan view seen from above of FIG. 63;

[0100]FIG. 65 is a side view showing a character in the condition inwhich it has returned to its original position;

[0101]FIG. 66 is an action flow chart of this operation;

[0102]FIG. 67 is a motion diagram of a model represented by collisiondetermination processing of an irregularly shaped zone and a model; and

[0103]FIG. 68 is a view given in explanation of a coefficient wherebyleaves are affected by wind depending on the respective heights of theleaves in flying material motion processing of FIG. 4.

BEST MODE FOR CARRYING OUT THE INVENTION

[0104] Preferred embodiments of the present invention are describedbelow with reference to the drawings, in respect of a video gamesmachine constituting an image processing device.

[0105] First Embodiment

[0106] A first embodiment of a video games machine is described withreference to FIG. 1-FIG. 33.

[0107] Description of the Hardware

[0108]FIG. 1 is a block diagram of this video games machine. Respectiveimage generation and processing No. 1 to No. 6, to be described, areexecuted by this video games machine.

[0109] This video games machine comprises: a CPU block 10 that performscontrol of the device as a whole, a video block 11 that performs displaycontrol of the game screen, a sound block 12 that generates effectssounds etc., and a subsystem 13 that performs reading of a CD-ROM.

[0110] CPU block 10 comprises an SCU (System Control Unit) 100, main CPU101, RAM 102, ROM 103, sub CPU 104, and CPU bus 105 etc. This block isthe heart of the image processing device of the present invention. MainCPU 101 incorporates a DSP (Digital Signal Processor), which executescomputer programs at high speed. RAM 102 stores polygon data of varioustypes that are sent to it from subsystem 13 that reads the CD-ROM, andis also employed as a work area of the main CPU 101.

[0111] ROM 103 stores an initial program for initial processing in theinitial condition of the device. SCU 100 governs the transfer of datathat is performed through bus 105, 106 and 107. Also, SCU 100incorporates a DMA controller that sends the image data required duringrunning of a game to VRAM in video block 11. Control pad 2 b functionsas means for information input by the user and is equipped with variousbuttons needed for operation. Sub CPU 104 is called an SMPC (SystemManager & Peripheral Controller) and has the function of collectingperipheral data from controller 2 b in accordance with requests frommain CPU 101. Main CPU 101 performs processing such as movement of animage displayed on a display in accordance with peripheral data sent toit from sub CPU 104. Sub CPU 104 identifies the peripheral equipmentthat is connected to connector 2 a (terminal of the main unit) andcollects peripheral data in accordance with the communication systemcorresponding to the type of peripheral equipment that has thus beenidentified.

[0112] Video block 11 acts as means for figure generation and comprisesa VDP (Video Display Processor) 120 for generating an image displayedusing polygons and aVDP 130 that performs image synthesis, shadedsurface processing, and clipping for the background image. It isconnected to VDP 121 and frame buffers 122, 123. When an image to bedisplayed on the display is generated in virtual space, the polygon datanecessary for display are sent from CPU 101 through SCU 100 to VDP 120and are written to VRAM 121. The polygon data written in VRAM 121 arestored in image-drawing frame buffer 121 or 123 as image-drawing dataincluding color information of 16 bits or 8 bits per pixel. Theimage-drawing data that are stored are sent to VDP 130. Main CPU 101supplies control information to control image drawing through SCU 100 toVDP 130. VDP 130 controls the image-drawing data in accordance with thiscontrol information.

[0113] VDP 130 is connected to VRAM 131 and comprises a scroll functionwhereby the entire display screen is shifted vertically or horizontallyor is rotated and a priority function (Z sort or Z buffer) thatdetermines the order of display of polygons. VDP 130 outputsimage-drawing data through memory 132 to encoder 160. Image-drawing dataoutput to encoder 160 is converted to video-signal format and is thensubjected to D/A conversion and displayed on monitor device 5. An imageis displayed on monitor device 5 based on this video signal.

[0114] Sound block 12 comprises a DSP 140 that performs audio synthesisby the PCM system or FM system and a CPU 141 that controls DSP 140. Theaudio data generated by DSP 140 is output to two speakers 5 a or 5 b byD/A converter 170 after conversion to a two-channel signal. Subsystem 13includes a CD-ROM drive etc. and is equipped with a function of readingapplication software supplied by a recording medium such as a CD-ROM anda generating video etc.

[0115] The processing performed by an image generating device asdescribed above will now be described. FIG. 2 is a flow chart showingthe main processing executed by CPU block 10. The following are executedin sequence: circular movement processing S200 for moving a character ina circle virtual friction processing step S202, display of a shadow onthe ground when there is a difference of level (S204) i.e. projectiondisplay processing of a character, intersection determination processing(S206), character motion processing control (S208), and character leveldifference processing (S210). Processing which is not essential is notperformed but is shifted to subsequent processing. The content of eachprocessing is described in detail below.

[0116] Circular Movement Processing

[0117] In general terms, the effect of this processing is as follows.When a direction key 26 b (also see FIG. 26) formed with a + on controlpad 2 b, to be described, is operated to the left or the right in theFigure, the character (warrior) 30 that is operated by this directionkey (see FIG. 3) is moved in the vertical or horizontal direction invirtual space. In circular motion processing mode, a virtual centripetalforce (force directed to the other side's character is applied between awarrior 30 operated by the player and a warrior 32 operated by the otherside, causing processing 30 to be executed whereby warrior 30 of theplayer automatically goes round (circular motion) the other side'swarrior. The details of this processing will now be described withreference to the flow chart of FIG. 4. In step 400, a determination ismade (determination 1) as to whether the circular motion processing modehas been entered or not. A circular motion request is deemed to havebeen made if the player has performed a prescribed operation. This maybe for example pressing of a prescribed button on the controller (pad 2b). Next, by for example reading the amount of operation in theleft/right direction in the drawing of the direction key 26 b of FIG.26, the position of the player's warrior and the other side's warriorare detected and the direction that the other side's warrior presentswith respect to the player's warrior is calculated (step 402).

[0118] Next, an angle in this direction is applied to the player'swarrior 30 and virtual centripetal force towards the other side'swarrior is applied to this warrior (step 404). Considered physically,this centripetal force is equivalent to an attractive force actingbetween the two objects.

[0119] If the x co-ordinate and z co-ordinate of the other side'swarrior are respectively taken as (exp, ezp), and the x co-ordinate andz co-ordinate on the other side's warrior are respectively taken as(mxp, mzp), the direction of the other side's warrior 32, as describedabove, is calculated from: arctan (exp-mxp, ezp-mzp). For convenience,the y-direction co-ordinate i.e. the height direction of the warriors onboth sides is neglected in this calculation.

[0120] As a result, circular motion in virtual space is produced (step406) in accordance with the speed in the horizontal direction producedby the transverse direction key and the centripetal force. By means ofthis circular motion, the player's warrior 30 is made to move around theother player's warrior 32 whilst facing the other player's warrior. FIG.5 is a conceptual diagram seen from above in virtual space of thiscircular movement, in which a warrior 30 performs circular movement fromcondition 1 through condition 2 and condition 3 to condition 4. FIG. 3described above is an image in virtual space according to condition 1displayed from a prescribed viewpoint, being the image displayed onmonitor 5 described above (see FIG. 1). FIG. 6 is an image like that ofFIG. 3 relating to condition 4.

[0121] Consequently, with the circular movement processing described, asingle character is given a virtual centripetal force, so the player,simply by operating direction key 26 b of FIG. 26 in the horizontaldirection in the drawing, can easily apply a circular movement tocharacter 30. For example, movement whereby warrior 30 which [theplayer] is himself operating moves around the other side's warrior 32 asdescribed above can easily be implemented.

[0122] Virtual Friction Processing

[0123] The effect of this processing is that the movement of thecharacter is made more varied by altering the slippage in the movementof the character depending on the slope of the ground surface and thefrictional force acting on the character in accordance with the natureof the ground surface, and applying dynamic friction when the characteris moving and static friction when the character is not moving. First ofall, FIG. 7 shows a cross-section of the ground surface in virtualspace. As shown in FIG. 8, the amount of slippage is calculated asfollows from the slope of the ground surface in step 800.

Amount of slippage (=dv/dt)=ivg

[0124] where

[0125] i is a prescribed constant

[0126] v is a unit normal vector expressing the slope of the groundsurface

[0127] and

[0128] g is the acceleration due to gravity.

[0129] As shown in FIG. 7(1), the unit normal vector is a normal vectorwith respect to the tangential direction to the ground surface. When theangle (θ) that this normal unit vector makes to the co-ordinate axis (xaxis) in virtual space gets large, a larger amount of sliding(acceleration) tending to descend along the sloping ground surface isapplied to a character who is on this ground surface.

[0130] Next, in step 802, a determination is made as to whether thecharacter (warrior) is moving or not. This is done for example from thepoint of view of the player by determining whether or not the directionkey for controlling movement of the warrior is being operated(determination 1).

[0131] If the character is moving, dynamic friction is applied; if thecharacter is not moving, static friction is applied (steps 804, 806).The friction (=dv/dt) itself is calculated as follows.

M·(dv/dt)=μ·S·M(g·cos θ+(dv′/dt)·sin θ)

dv/dt=T·g·cos θ+T·(dv′/dt)·sin θ)

[0132] where M is the weight

[0133] v is the frictional speed (speed of the object after calculation)

[0134] v′ is the speed of the object

[0135] μ is the coefficient of friction

[0136] S is the ground-contacting area of the character (constant)

[0137] g is the acceleration due to gravity (constant)

[0138] θ is the angle of the ground surface

[0139] T=μ·S

[0140] The dynamic friction and static friction are determined byapplying prescribed processing to the friction (or coefficient offriction) obtained by this expression. The static friction has a largervalue than the dynamic friction. This friction changes depending on theangle of the ground surface, the friction being smaller as the slope ofthe ground surface is increased.

[0141] Next the attributes of the ground surface are determined. Thatis, it is determined whether the surface on which the character isgrounded is for example a water location or a sandy location. Theseattributes are applied virtually beforehand to each ground surface. Forexample, the amount of friction calculated in the case of a sandylocation is taken to be doubled and the amount of friction in the caseof a water location is taken to be tripled. This is then reflected (step810) so as to subtract this frictional force from the amount of slippagethat was previously calculated. Thanks to this processing, staticfriction or dynamic friction is constantly applied to the character, soonce a character has stopped it will not readily move off again, butonce it has started moving it becomes easier to move. Also, the movementcharacteristics of the character can be-altered depending on theattributes of the ground. By this means, movement of a character can berepresented very realistically.

[0142] Display of shadow on to a ground surface having a leveldifference:

[0143] As shown in FIG. 9, the effect of this processing is that, whenthere is irregularity 91 of the ground surface 90 on which character 91is standing, the shadow (projected image) of the character can berepresented by a simpler calculation whilst applying irregularity tothis ground surface. An outline of this processing is shown in FIG. 9.92 in this Figure is a virtual reference line of height 0 and 96 is aparallel light source at infinite distance. This character isconstituted of a set of objects such as head, breast, abdomen, hips andlegs etc. Each object is created by a plurality of polygons. yG in thedrawing is the distance from the base line to the ground surface wherethe character is standing and y1 . . . yn are the distances from eachobject to the base line. This processing is calculated using thefollowing expression.

E′(x′, y′, z′)=Ms·E(x, y, z)

[0144] a where E′(x′, y′, z′) are the co-ordinates of the shadow. E(x,y, z) are the co-ordinates of the character and Ms is the matrix (matrixexpression) for converting the shadow co-ordinates to the worldco-ordinate system. This Ms is given as follows.

Ms=Mu·(−Tyg)·Pn·Tyn·(−Tsn)·Rn·Tsn

[0145] Mu is a conversion matrix for converting the co-ordinates of thecharacter to the world co-ordinate system of FIG. 9. Tyg is a parallelmovement matrix for producing parallel movement from the ground surfaceon which the character is standing up to the base line.

[0146] Pn is a conversion matrix for slantwise projection of thecharacter on to the base line.

[0147] Tyn is a matrix for effecting parallel movement of the slantwiseprojected shadow to the ground-contacting point of each object (i.e. theground surface where each object is located). Tsn is a parallel movementmatrix for effecting parallel movement of each object with respect tothe origin of the world co-ordinate system.

[0148] Rn is a matrix for rotating shadow polygons in accordance withthe slope of the ground. This processing is carried out by the followingsteps.

[0149] Processing step 1: Human-like character 91 for creating a shadowis subjected to parallel movement from the ground surface to base lineof height 0; then

[0150] Processing step 2: This human-like polygon set 91 is projectedslantwise on to reference line 94 using parallel light source 96; then

[0151] Processing step 3: The slantwise projected objects arerespectively moved in parallel for each object with width y1 . . . yn asfar as the ground surface; then

[0152] Processing step 4: Each object is moved in parallel from theposition of the world co-ordinate system up to the origin of thissystem; then

[0153] Processing step 5: Each object is rotated in accordance with therespective angle of the ground surface; and finally

[0154] Processing step 6: Parallel movement is performed to return theobjects that have been moved to the origin by processing step 4 to theiroriginal co-ordinate system. Consequently, by this processing, if thereis irregularity in ground surface 90, the projected image of a charactercan be displayed in a simple manner on ground surface 90 incorporatingsuch irregularity in a manner matching this irregularity.

[0155] Intersection determination processing:

[0156]FIG. 10 is a xz plan view showing the region of the field-of-viewof a virtual camera that picks up two characters, for example warriorsfacing each other (character 1, character 2). An image as shown in FIG.3 already described is displayed by this virtual camera (viewpoint). Inthis processing, when this field-of-view region is overlaid by virtualstructural objects other than the warriors, such as walls or buildingsthat screen the field-of view region, arrangements are made not todisplay some or all of such structural objects. In FIG. 10, whilestructural objects 100, 102 screen the field-of-view region from theviewpoint to the character, structural object 104 does not obstruct theregion of the former, notwithstanding that, depending on the viewpoint,it is in the displayed region. In this case, image generation or imageprocessing is performed to delete structural objects 102 and 104. FIG.11 is a flow chart showing this processing. In this processing, in orderto speed up and facilitate the determination of whether or not suchstructural objects overlay the field-of-view region, the determinationis performed in the xz co-ordinate plane, and objects having thicknessare approximated by circles. FIG. 12 is a xz plan view showing how sucha structural object is approximated by an inscribed circle.

[0157] In FIG. 11, step 110 is the processing to determine whether ornot this approximation circle overlays the field-of-view region. FIG. 13is a conceptual view of the determination performed in this step. Thedetermination as to whether a given approximation circle having radius tof centre point T is overlying or not is performed by the followingprocessing for all the sides constituting the triangular regioncorresponding to the field-of-view region from the viewpoint tocharacters 1 and 2. In the following description, vector L, vector R andvector T are the vectors to L, R and T from a prescribed origin. Point Land point R are set sequentially for the respective vertices of eachside of the triangle. [Mathematical expression 1]

r^(→)=R^(→)−L^(→)

t^(→)=T^(→)−L^(→)

p^(→)=c^(→)+L^(→)−T^(→)

cx=rx·¦c^(→)¦/¦r^(→)¦, cy=ry·¦c^(→)¦/¦c^(→)¦

[0158] where:

[0159] [Mathematical expression 2]

¦c^(→)¦=¦t^(→)¦ cos θ

[0160] cx is the x component of vector c

[0161] cy is the y component of vector c

[0162] rx is the x component of vector r

[0163] ry is the y component of vector r

[0164] From the definition of the inner product, [Mathematicalexpression 3]

¦r^(→)¦=¦t^(→)¦ cos θ=rx tx+rz tz

¦c^(→)¦/¦r^(→)¦=(rx tx+rz tz/¦r^(→)¦²=(rx tx+rz tz)/(rx²+rz²)

[0165] where [Mathematical expression 4]

0≦¦c^(→)¦/¦r^(→)¦≦1

[0166] If the centre T of the approximation circle is within thepositive region of straight line TR (if T is outside the inside of thetriangle), if

[0167] [Mathematical expression 5]

¦p^(→)¦−d>0

[0168] the circle is independent with respect to the region within thetriangle i.e. it does not overly this region; if [Mathematicalexpression 6]

¦c^(→)¦/¦r^(→)¦<0 or

1<¦c^(→)¦/¦r^(→)¦

[0169] if point T is in the positive region of straight line LR, thecircle is independent with respect to the region.

[0170] Instep 110, if the approximation circle does not overly theinternal region of the triangle, processing is performed (step 111) suchthat this structural object is not displayed; if it does not overlythis, processing advances to the next step (step 112). The effect of thenext processing is to perform a determination as to whether there isoverlapping in respect of a structural object such as a wall where thisstructural object has length in a fixed direction. This processing isperformed as follows as shown in FIG. 14. For a structural object thatcan be approximated as a straight line TS, a determination is made as tothe intersection (a type of overlap) of this straight line and thetriangular region. The following processing is performed for all sidesconstituting this triangular region. If the function for determining thepositional relationship of the straight line LR and an arbitrary point Pis taken to be F1 (P), [Mathematical expression 7]

F1 (P)=a1 Px+b1 Pz+c1

a1=Lz−Rz

b1=Rx−Lx

c1=Lx Rz−Rx Lz

[0171] If the function for determining the positional relationship ofstraight line ST and an arbitrary point P is taken to be F2 (P),[Mathematical expression 8]

F2 (P)=a2 Px+b2 Pz+c2

a2=Sz−Tz

b2=Tx−Sx

c2=Sx Tz−Tx Sz

[0172] If F1 (S).F1(S)<0 and F2 (S).F2(S)<0, it is determined thatstraight line TS intersects straight line LR. If this intersection isdenied, processing shifts to step 114 and the determination is made towhether there is overlap with the approximation circle. The reason forthis is as follows. If the straight line TS described above enters fullywithin the region of the triangle, the result of the overlap decision isnegative and the wall-shaped structural object would be displayed.Accordingly, a small circle 150 corresponding to the thickness of thewall as shown in FIG. 15 is associated with this straight line TS and adetermination of overlapping is performed in respect of this smallcircle in the same way as in step 110. As a result, if thisapproximation circle enters the region of the triangle, even if straightline TS enters completely into the triangular region and thedetermination made in step 112 is that there is no overlap, it isconcluded that overlap does take place and processing shifts to step111.

[0173] By such processing, it can be arranged that structural objectssuch as walls, fences, or screens in the field-of-view region from thevirtual camera to the character to be displayed are not displayed.However, if, as shown in FIG. 10, this structural object such as a wallprojects beyond this field-of-view region as shown at 104, thisstructural object is still displayed. By the above processing, characterdisplay can be effected in the most suitable manner without thecharacter being hidden by unnecessary structural objects. Of course,when the character in question is absent, such structural objects aredisplayed as normally. As the approximation circle, a circumscribedcircle could be employed as shown in FIG. 12 instead of an inscribedcircle.

[0174] Character motion processing control

[0175] The effect of this processing is to form interpolation such thatthe final position of a single motion is matched to a target point, whenit is desired to effect display in series from a single motion withoutlinkage of other motions.

[0176]FIG. 16 shows a series of steps of motion of a single character;the steps are shown whereby a human-like character (warrior) 160delivers blows using arm section 160A to another warrior by operation ofpad 2 b by the player. This action of the arm part is displayed on themonitor by calculation by means of a well-known spline function (inparticular, a third-order spline function). If now at this point it isassumed that this arm part 160A is moving towards the breast part of theother warrior, and, at a certain time point, the other warrior moves inthe y direction (for example, suddenly stoops), from the point of viewof the player, it is very difficult to suddenly change the track of themoving arm to downwards as in FIG. 17 and also if CPU block 10 simplyattempts to do this, the movement of the arm can easily becomeunnatural.

[0177] Accordingly, a link region is provided in the vicinity of thetermination of the spline track alteration process of the motion that iscurrently being executed, and interpolation such as applying a newspline function is performed in this link region such that the terminalpoint of the initial spline track becomes a target point in anotherposition.

[0178] This will now be described with reference to the drawings. Asshown in FIG. 18(1), the fist 180A that is at the tip of the arm part ofthe warrior of FIG. 16 is moving along a track 180 determined by aspline function. FIG. 18(2) shows the track 180 obtained by this splinefunction; fist 180A moves from the starting point of this track until itreaches the end point and then returns to the starting point.

[0179] Let us now assume that fist 180A is moving from the startingpoint of spline function track 180 towards its end point. Let us assumethat, in this process, due for example to a change in the behaviour ofthe other warrior, the need arises to alter the initial end point to atarget point.

[0180] Accordingly, at the time point where the position 180A of a fistis in the link region, CPU block 10 corrects the function in this regionsuch that it terminates at the target point. This interpolation isperformed for example as follows. Of course, this could also be achievedby suitably altering the degree and/or coefficient of the splinefunction in the link region. As a result, the motion shown in FIG. 16 isautomatically interpolated to the motion shown in FIG. 17, and themotion in the link region can thereby be represented more smoothly. Itshould be noted that, for convenience in illustration, the vertical axisin FIG. 18(2) shows only the amount of movement in the y axis direction.In accordance with the general conventions of three-dimensional videogames, the x axis is given in the transverse direction when looking atthe monitor screen, the y axis is given in the height direction, and thez axis is given in the depth direction i.e. the direction perpendicularto the screen. The link region (link time) is appropriately set up bymeans of a group of a plurality of frames comprising an end frame. Also,interpolated motion of the entire arm is effected by applying similarprocessing for the objects other than the fist, namely the upper armpart and lower arm part. The interpolated co-ordinates in the linkregion are set by means of the following characteristic expression:Current co-ordinate+(current co-ordinate−target co-ordinate).

[0181] (Current Time/Link Time)

[0182]FIG. 19 is a flow chart given in explanation of the aboveprocessing; in step 190, a determination is made as to whether a motionmovement command has been generated by operation of pad 26 b by theplayer. In step 192, a determination is made as to whether a targetpoint whose co-ordinates are different from the end point has been set.In step 194, the selected motion is reproduced. In step 196, if theresult of this determination is positive, the link time is calculatedand processing shifts to step 194, in which the motion interpolatedduring this link time is reproduced. In step 198, a determination ismade as to whether or not the current frame is the end frame of themotion series and, if it is the end frame, processing returns to themain routine; if the end frame has not yet been reached, processingreturns to step 192.

[0183] In this process, the link frames constituting the link timerepresent 0.1 of the maximum number of frames of the motion (number offrames from the start frame of FIG. 18(2) to the end frame); if the linkframes exceed 10, [their number] is fixed at 10. The number of linkframes should be in the range of at least 1 to ½ of the maximum numberof frames. If the link frames are too long, the original movement of themotion is lost; on the other hand, if they are too short, interpolationbecomes abrupt and smoothness of the motion is lost.

[0184] The following benefits are achieved by this processing. When, asin a video games device, the controller is operated in order to rapidlyoperate a character such as a warrior appearing on the game screen,varied movements of the character are continuously reproduced. At a timepoint when a series of motions is reproduced, even though [the player]tries to alter the motion to match rapid actions of the other character,so long as the motion itself is fixed, this is difficult. However, ifmotion is interpolated as described above, the motion matching themovements of the other character for example can be reproduced in avaried manner, making the motion more realistic. Usually, suchinterpolation is extremely difficult for a user to perform andconventional video games devices are particularly ill-constructed toperforming such interpolation.

[0185] It should be noted that, while this processing has been describedtaking as an example the case where the motion was calculated using aspline function, this processing could be applied to pattern changesystems in which a predetermined pattern is sequentially reproduced. Insuch cases, it may be arranged to reproduce a corrected pattern in thelink region.

[0186] Character Level Difference Processing

[0187] The effect of this processing is to display a desired image inwhich this level difference is corrected when there is a mutual leveldifference between a character (warrior) and the ground. For example, asshown in FIG. 20, when there is a level difference between two warriors200, 202 that are facing each other, it is unrealistic if punching froma warrior 200 to a warrior who is on a higher level is performedhorizontally. Accordingly, this processing is designed to perform theassault from warrior 200 directed in the higher direction, correctingfor this level difference (see FIG. 23).

[0188] In this processing, as shown in FIG. 21, in step 2100, adetermination is made as to whether this level difference needs to becorrected. Such a determination “correction required” is made if anattack request (command) for assault using arms or legs from one warriorto another warrior is generated in respect of mutually facing warriorsfor example as in the drawing. If the result of this determination isnegative, next, processing returns to the main routine. On the otherhand, if the result of this determination is positive, further, in step2102, a collision determination is performed between the character andground i.e. to establish whether the other warrior is standing on theground; if the result of this is positive, character level differenceprocessing is deemed to be necessary, and processing shifts to the nextstep. If this determination leads to a negative result, the routine inthe Figure is terminated.

[0189] Next, in step 2104, the distance from the ground on which thecharacter controlled by the player is standing to the aforementionedcharacter is calculated. The same calculation is performed for the othercharacter also. Next, in step 2106, the value of this result is comparedwith a prescribed value, and, if the range of the prescribed value isexceeded, processing is performed to keep the difference relating tothis distance within this range. Specifically, if we let the height of awarrior operated by one player be (my) and the height of a warrioroperated by another player or operated automatically by a prescribedprogram by the image processing device itself be (ey), the difference(diff1) between these two is (my−ey). An evaluation is then performed asto whether for example diff1 is within the range −0.15 ≦ diff1 ≦0.15,and, if diff1 exceeds this range, a diff1 smaller than this range istaken as being −0.15 and a diff1 greater than this range is taken asbeing 0.15, while a diff1 within this range is directly determined as(diff2) without modification. The reasons for carrying out thiscorrection on diff1 will be described later.

[0190] In the next step 2110, diff2 is divided by the time (number offrames) for which attacking force is generated and the result is takenas “result 1”; the result obtained by dividing diff2 by the time fromgeneration of the attacking force until hardening is dissolved is takenas “result 2”. This will be described using FIG. 22. FIG. 22 shows theflow of an attacking move (kick, punch or jump etc. executed by thewarrior); this is as follows in respect of the flow of frames (flow oftime) for each time 1, 2 . . . 5.

[0191] 1: commencement of the move (frame number 0)

[0192] 2: attacking force generated (frame number 1 to frame number 3)

[0193] 3: attacking force dissipated (frame number 3 to frame number 4)

[0194] 4: hardening time (this is a time in which commands for otherattacking moves are not accepted and may be from 0 to 4 frames)

[0195] 5: end of the move (from frame number 0 to 5)

[0196] “Result 1” described above is therefore: (diff2)/2 and “result 2”is (diff2)/(4 −2). These values are of course set and stored in aprescribed work RAM region. The characteristic shown in FIG. 22 ispredetermined for each move. Result 1 is a value corresponding to therate of change of each frame until attacking force is generated andresult 2 is a value corresponding to the rate of change of each frameuntil hardening is dissolved.

[0197] Next, the co-ordinates whereby the hands and/or feet etc. movewhen a move is executed are determined for each requested move in step2112. The seco-ordinate values are determined before and under theassumption that there is no difference of level with respect to theother character. This co-ordinate (leaf) is taken as “result 3”. Thisleaf is determined in accordance with the spatial coordinate position ofthe hand or foot when a move is executed by a function fat for returningthe leaf. The processing when an attacking move is executed is describedbelow with reference to the following and subsequent steps.

[0198] After a move has been generated, in step 2114, detection iscarried out to ascertain the serial number of the frame to which thecurrently displayed frame corresponds. In the next step 2116, it isdetermined whether or not this frame is a frame prior to generation ofattacking force. In the Figure, it is determined that frames up to frame1 are frames prior to generation of attacking force.

[0199] Next, if the result of this determination in step 2116 ispositive, in step 2118, this “result 1” and the frame number aremultiplied and the result of this calculation is added to the leaf ofthe step 2112 as a difference. Using this result, the shape of the bodyof the warrior is then recalculated using the value etc. obtained byadding this difference to the lease¹, using the known inverse kinematictechnique (see for example “Dynamics And Control Of Robots”, compiled bythe System Control Information Association, by T Arimoto, published byAsakura Shoten, 5.2 Reverse kinetics (page 132˜)).

[0200] In step 2116 already described, if it is determined that [theframe] is a frame subsequent to that in which attacking force isgenerated, in step 2200, the current frame number (“2 or 3”) in theFigure, is subtracted from the frame number (“4” in the Figure) at whichhardening is dissolved, and processing shifts to the step where thisframe number is multiplied by result 2.

[0201] As a result, as shown in FIG. 23, by step 2118, a punch isexecuted from the warrior 200 which the player himself controls towardsthe other warrior 202, with a height in which the level difference ofthe warriors is compensated; the arm that executed this punch is thenreturned to its original position whilst effecting level compensation,whether the punch hit its target or not. With the processing that hasbeen described, image processing is executed that reflects thedifference in level of the two warriors, so an attack (punch or kick)that is performed by a single warrior is carried out to a warrior in ahigher location and images matching the current situation of the actualattack can thereby be provided. Consequently, even without storingbeforehand in memory motion in respect of a warrior in a higherposition, image processing between one character and another charactercan be implemented in a condition reflecting the level differencebetween the characters. Incidentally, the reason why diff1 is correctedis as follows. If such correction were not carried out, when there is alarge level difference between the two warriors, in an extreme case, theassault from one warrior to another warrior could be directed in thedirection at right angles with respect to the ground, which would itselfbe unnatural.

[0202] It should be noted that, although in the explanation of thevarious processes described above, the example of a video game wastaken, there is no restriction to this. If FIG. 1, a ROM cassette couldbe employed instead of a CD-ROM. These function as memory media in whichthe operating program of an image generating device according to thepresent invention is stored. Also, in the intersection determinationprocessing, the case where a structural object as already described isdisplayed incompletely and in the case where this structural object isdisplayed using for example mesh polygons or poly lines are to be takenas being covered by the mode “not displayed”. FIG. 24 and FIG. 25 arerespective examples of a human-like character (warrior) constituting amodel according to the present invention.

[0203] In glow shading by CPU block 10 (the same applies to other typesof shading), processing may be performed not only for all the polygonsof a character but also for only part of a character, in particular fora portion which it is desired to show threedimensionally by linearinterpolation of color (for example, polygons corresponding to exposedskin). In this way, the load on CPU block 10 during execution ofprocessing can be reduced. In the case of the character of FIG. 24, glowshading may be performed only in respect of the fist, face, and chestbelow the neck which are exposed from the clothing; in the case of thecharacter of FIG. 25, glow shading may be performed only in respect ofapproximately the upper part of the body and the feet.

[0204] Also, although conventionally in the case of a quadrilateralpolygon four vertices were employed when Z sorting was applied to thepolygons, it would be possible to determine this using only the point ofintersection (mid point) of the diagonals respectively joining twovertices. As a result, processing speed can be improved by reducing thefrequency with which the main CPU accesses memory. It should be notedthat, even though Z sorting is applied using such a mid point, the sameaccuracy as in the case of Z sorting using four vertices is stillmaintained, since this mid point represents the average value of thefour vertices. In the case of a triangular polygon, the centre ofgravity could be used.

[0205] Next, another embodiment of processing operation of the imagegenerating device described above will be explained. FIG. 26 is a frontview showing details of the control pad 2 b described above. Thiscontrol pad is provided with a direction key 26 b as described above andbuttons A, B, C, X, Y, Z, L and R. Pressing this direction key orbuttons corresponds to movement of a character (warrior) of FIG. 24 or25: for example, button A corresponds to “defensive action againstattack from another warrior”, button B corresponds to “punch otherwarrior” and button C corresponds to “kick aimed at other warrior”.

[0206] The user i.e. the player controls a character as he wishes byoperating this key and/or buttons in various manners; however, a greatdeal of practice is required in order to control a warrior moving veryrapidly and with great versatility in an appropriate manner.

[0207] Accordingly, in a mode of the processing described herein, asshown in FIG. 27, a set of command moves constituted by pressingcombinations of a plurality of buttons are designated as “combinationmoves” and these are stored beforehand in working RAM as a file. Then,by reading these by pressing one of the buttons described above, thewarrior can be made to execute the command moves in sequence. In FIG.27, PPK is equivalent to pressing button B, button B and button C insequence and P+K is equivalent to pressing button B and button Csimultaneously. In addition, the number of frames to be occupied bythese moves can be set for each command move. Consequently, the playercan create combined moves in versatile fashion as he wishes since he canfreely set the number of frames of each command move in a combinationmove. A specific example of such a combination move is “throwing theother warrior over one's head, and kicking him when he gets up”.

[0208] Continuing the description in more detail, “P, K, P” indicatesthat the punch button, kick button and punch button are continuouslypressed and, if we assume that an overhead throw is performed ifcontinuation of these is determined, when P is pressed, the charactergoes into the punch motion. If K is pressed after the commencement ofthis motion but for example before the motion goes into punch return, akick is commenced from the attitude of a delivered punch and with thetiming of the punch return motion; if P is input whilst the kick motionis being executed, this is deemed as a continuous move and continuanceis effected with the overhead throw motion (command move). If the timingat this point is made to coincide with the timing at which the othercharacter is about to fall over, a very effective overhead throw can becreated in which moves are easily applied to the same overhead throw. Aplayer can create a plurality of such combination files and allocate asingle button to each file. of course, if the player presses a button towhich no such combination file has been allocated, the single move thatwas originally allocated to this button is executed. What range ofbuttons are to be used to register combination moves may be suitablydetermined in accordance with requirements for combination moves andrequirements for single movements. A plurality of buttons could beallocated to individual files.

[0209] Next, the operation of this processing will be described withreference to the flow chart shown in FIG. 28. First of all, in stepS280, a determination is made as to whether a button as described abovehas been pressed. If a button has been pressed, if a combination move isregistered in respect of the button that has been pressed (step S282:affirmative), in step 284, the commands in the combination movesregistered in working RAM (equivalent to pressing plural or singlebuttons) are sequentially read. Next, in step S286, a determination ismade as to whether or not the command in the file has been executed asfar as its end; if this is affirmed, this flow chart is repeatedlyexecuted until it terminates. In contrast, in step S280, if no buttonhas been pressed, return is effected; and, in step S282, if nocombination-move file is registered for a button that is pressed, thesingle move allocated to this button is executed.

[0210] In the presently described mode, a combination of action commandsto a character (model) (e.g. combination of operating switch presses:pressing a single switch, pressing a plurality of switches, pressing theswitches in sequence, or pressing the switches simultaneously) is storedin memory; the means for image processing reads this by a simple switchoperation such as for example pressing a single button, and the movement(motion) of the model is continuously controlled in accordance with thegroup of commands that are thus read. Consequently, as described above,the user can represent more versatile movement (motion) of the model ashe wishes, without complicated key operation.

[0211]FIG. 29 shows the initial screen for mode selection that isdisplayed on the monitor when combination processing as described is tobe performed: in order to select a combination move, an icon at the topright is selected. FIG. 30 is a screen showing the case where a button(key) has been assigned to a move; FIG. 31 is a screen for compilationof the combination-move file; and FIG. 32 is a screen showing onecondition wherein warriors are in mutual combat condition. FIG. 33 is ascreen that is deployed later on the screen of this one condition andshows a condition in which a warrior (“Akira”) has been knocked down bythe warrior (“Rau”). It should be noted that, as can be seen from FIG.33, when one warrior has knocked down another warrior (when this hasbeen determined by the CPU block), the character 330 on the screen ismade to display this. In FIG. 33, this is displayed by changing a“plant-like bud character” to a “plant-like open-flower character”.

[0212] Second Embodiment

[0213] Next, a second embodiment of a video games machine constitutingan image processing device will be described with reference to FIG.33˜FIG. 68. Since the hardware construction of the video games machinein this second embodiment is the same as in the case of the firstembodiment described above, description thereof is omitted.

[0214]FIG. 33 is a flow chart showing the main processing executed byCPU block 10; the processes described below are executed. S200 is aresidual image processing routine, S202 is a routine for churning-upprocessing (processing of flying material); S204 performs modelfree-fall movement processing, S206 performs processing fordetermination of collision between the model and an irregularly shapedzone, and S208 performs processing for alteration of playback speed.These processes are executed repeatedly. Each of these processes will bedescribed below. Residual image processing

[0215]FIG. 35 shows the principles of residual image processing appliedto a warrior constituting a model. In FIG. 35, 30 is a warrior andresidual images are displayed in respect of the warrior's leg 30B.Specifically, simultaneously with the display of the actual image of thecurrent frame, residual images 1 to 4 of the previous frames areconcurrently displayed.

[0216]FIG. 36 shows the principles of this residual image processing.The polygon data file (or parameter file) stores parameters thatdetermine the motion (revolving kick) of the leg of this warrior. #1 to#n of the polygon data file show the number of frames from the timepoint of residual image commencement.

[0217] In polygon data file #1, a model #1 corresponding to residualimage 4 is stored. Model #1 of the warrior is therefore displayed asactual image on the screen at this time point. At the next time point,model #2 corresponding to residual image 3 is stored in polygon datafile #2. Model#2 of the warrior is therefore displayed as actual imageon the screen at this time point. Subsequently in the same way,warrior's leg models #3 . . . , #n are displayed on the screen. In thecase of the fourth frame (#4) of FIG. 4, #1 to #4 are successivelydisplayed as the actual image model of the leg.

[0218] B#1, B#2, B#3 and B#4 are provided as buffers for the residualimages. The warrior motion data recorded in the polygon data files aresuccessively recorded in these buffers. This is displayed in the bottomportion of FIG. 36. The data of model #1 that is stored in polygon datafile #1 is stored in residual image buffer #1 after residual imagecommencement; at the next time point, the data of model #2 that isrecorded in polygon data file #2 is stored in residual image buffer #1,and the content of residual image buffer #1 is sent to residual imagebuffer #2. That is, the residual image buffer data is transmitted in theorder #1→#2 →#3→#4, and the actual image motion data in the one-previousframe are sent from the polygon data file to residual image buffer #1.Residual image buffer #4 is successively directly updated.

[0219] For example, at the time point of the fifth frame, motion data ofmodel #5 is stored in the polygon data file and this model is displayedas actual image. Motion data of model #4 is stored in residual imagebuffer #1, motion data of model #3 is stored in residual image buffer#2, motion data of model #2 is stored in residual image buffer #3, andmotion data of model #1 is stored in residual image buffer #4.

[0220] Since the motion data of the polygon data file and the data ofthe residual image buffers (equivalent to previously calculated motiondata) are displayed simultaneously, the actual image and the residualimages are simultaneously displayed on the screen. This is shown in FIG.35. Whereas display of the actual images is effected with ordinaryrendering, in the case of the residual image, in order to create abetter dramatic effect, in other words, in order to “show in the mannerof a residual image”, rendering is performed whilst applying processingfor semi-transparency. The degree of this semi-transparency may beincreased as the number of frames by which the residual image isprevious to the time point in question increases, the residual imagebeing displayed in more transparent fashion as the number of frames bywhich it is previous is increased. The residual image buffers are set upin RAM 102. Next, the operation of residual image processing in thisembodiment will be described. FIG. 37 is an outline flow chart of thisprocessing. First of all, it is determined whether or not residualimages are required (S500). This determination is made for example foreach motion. For example, residual images may be deemed as necessary andsuch processing performed for large-scale moves (rotating kick, backthrow etc.) involving large movements of the warrior. FIG. 35 may bereferred to. Otherwise, this is the same as in the case where the amountof action exceeds a prescribed value. FIG. 38 is a detailed flow chartof this processing for determining the necessity for residual images.First of all, a check is made to establish whether a move has beengenerated (S600). This check is made by ascertaining the operatingcondition of the control buttons and/or control stick of controller 2 bdescribed above. If it is ascertained that a move has been generated,the attributes of the move are read from data (S602). The move attributedata are data relating to the nature conferred on individual moves, forexample “attacking move”, “move using the feet”, “move using the hands”etc.

[0221] Next, it is determined (S604) whether this attribute data is datato the effect that residual images are to be generated or the reverse.For example, in the case of “attacking move” or “move using the feet”,residual image representation is deemed to be necessary and a prescribedflag “F” is set to “1” (S606); otherwise, “F” is set to “0” (S608).

[0222] In the next step of the outline flow chart, the location whereresidual images are required is identified (S502). This identificationis performed by the processing shown in FIG. 39, which is a detail flowchart. First of all, in S700, a check is made to establish whether ornot an attack command has been generated. An attack command is a commandgenerated by operation of a control button or control stick in acondition reached in a command mode such that an attack on anotheropposing warrior is made by a warrior controlled by the player.

[0223] In FIG. 39, when for example a rotating kick command is generated(the case of FIG. 35 corresponds to this), it is established byreference (S702) that the location of the attack is the ankle part (30Aof FIG. 35); then, in order to form a residual image of the entire leg,ankle 30A, leg 30B, and thigh part 30A i.e. the entire leg on the leftside (see FIG. 35) is identified as the site where residual images arerequired (S704). At this point, as described, it should be noted that awarrior is constituted of plurality of parts, each part beingconstituted of respective polygons. of course, it would be possible todisplay (S706) residual images even if an attack command is notgenerated. Of course, in this case, in the determination “are residualimages required?” in S500 of FIG. 37, the need for residual images isdetermined such that residual image representation is possible even when“currently attacking” is not the case. This could happen for example inthe case where the process of a warrior being knocked down by a move isdisplayed, accompanied by residual images. In this case, the part whereresidual images are needed is determined from the motion data as in S702and S704.

[0224] Then, in S504 of FIG. 37, residual image display as described inFIG. 35 is executed; on arriving at S506, a determination is made as towhether or not residual image display has terminated. For example, adetermination is made as to whether or not a series of motions hasterminated; in the example of FIG. 35, a determination is made as towhether or not the rotating kick has terminated: if it is determinedthat it has terminated, residual image display processing is terminated.

[0225] In this embodiment, the data of the polygon file having a seriesof movement data of a warrior are directly successively recorded in theresidual image buffers. In this polygon file, there are recorded theco-ordinates of each vertex of a polygon converted to co-ordinates andclipped, together with the normal vector at each point. Since thispolygon file data is directly recorded in the residual image buffers, itonly needs to be output together with the current actual image, soco-ordinate conversion (modelling) of polygons for use as residualimages on each occasion, as was done in the prior art, is unnecessary,thereby lightening the calculation load on the CPU block. Furthermore,since residual images are displayed in the past positions of a part(leg) and semi-transparent calculation is applied, the residual imagerepresentation can be displayed with considerable dramatic effect. Itshould be noted that, in addition to the semi-transparent calculation,the display of leg polygons could be represented by mesh-shapes or aline. By semi-transparent processing, the residual image of the leg andthe background are displayed simultaneously.

[0226] With this embodiment, large moves, to which residual images areaffixed, and medium or small moves, to which residual images are notaffixed, can be distinguished by the presence/absence of residual imagesby the visual sense of the player, thereby improving the realism of thegame (variation and interest of the image representation as a game).

[0227] Flying Material Movement Processing

[0228] Next, churning-up processing of flying material (ground material)will be described. As will be described, this processing provides a modewhereby sand orwater on the ground or leaves that have fallen on theground can fly up. A description concerning the first two of these willbe given first. The gist is as follows.

[0229] As shown in FIG. 35, when a warrior 30 performs motion involvingkicking upwards using his feet or a warrior lands from the air,processing is performed whereby water or sand is churned up. Suchprocessing is performed in order to raise the dramatic effect of thegame. In particular, in a video game such as a hand-to-hand fightinggame, in which the player seeks to control the character by rapidlyoperating the control buttons, the movements of the character are variedand rapid, so it is necessary to represent such churning-up of wateretc. by rapid and precise calculation matching the movement of thecharacter. The processing described below makes this possible.

[0230] First of all, churning-up processing of sand or water will bedescribed. In this connection, churning-up processing, as shown in FIG.40, comprises sequential movement along a track found by calculation ofa polygon of changing pattern (total of 32 patterns). These patternssimulate the condition of water or sand as it is sequentially scattered.If calculation were to be carried out for each particle of sand orwater, a long calculation time would be required; movement is thereforeperformed whilst applying a pattern change, taking many particlestogether.

[0231] In this processing, a parts check of the warrior is performed.The warrior consists of the parts: head, right hand (upper arm, lowerarm, wrist), left hand, breast, abdomen, hips, left leg (thighs, leg,ankle) and right leg. The parts check is performed for legs, head andhips. For example, [material] kicked up by the feet or falling from thehead or hips is therefore simulated. The parts check includes a check ofthe amount of movement of the parts. Apart from this, the attribute flagof the virtual ground surface and the parts position flags are checked.The virtual ground surface attribute flag (b water) is set to “1 (waterattribute)” or “0 (sand attribute)”, and the part position flag (b air)is set to “1 (grounded condition)” or “0 (aerial condition)”. If (bwater) is “1 (water attribute)”, churning-up of water is performed; ifit is “0 (sand attribute)”, churning-up of sand is performed. Thechurning-up of water or sand comprises the following modes.

[0232] Generation on landing: this is the case where the part lands on aground or water surface: sand or water is scattered in all directionsfrom the point of generation.

[0233] Generation by kicking up: this occurs in the condition in whichthe part is grounded on a ground surface (water surface); sand or wateris churned up in the direction of movement of the feet (part that isbeing checked) by being kicked up by the feet. Generation by kicking upand landing are shown diagrammatically in FIG. 60. 280 in the Figure isa character (warrior); sand or water 282 is churned up in response tothe movement characteristic of the feet by being kicked up by the feet.Alternatively, water or sand is churned up in all directions in responseto the landing action, on landing.

[0234] In this processing, processing, called continuation processing,is executed, which is continued for a period of a few interrupts (a fewscenes or a few frames) of occurrence of landing or occurrence ofkicking-up. Usually, at the time of such occurrence, the churning-upnumber is determined and set to ¼ thereof. If the churning-up number istaken to be N, the churning-up number is successively decreased asfollows with each interrupt. If the churning-up number is taken to be N:

First time: ¼N, N′=N−(¼)·N

Second time: ¼N′, N′′=N′−(¼) N′

[0235] Third time: ¼N′′

[0236] That is, it is set to ¼ in each case of the remainder of thechurning-up number at each interrupt. Regarding the mode of churning-up,a pattern change is arranged to be performed as already described.

[0237] Processing in the case of landing occurrence will now bedescribed. Let the position of the checked part on the previous occasion(i.e. one interrupt previous) be (OX, Oy, OZ), and the present positionbe (PX, Py, PZ). Let the height of the ground surface or water surface(Y co-ordinates) be epos.

Basic speed of the part: SPDX=PX−OX  X direction

SPDy=Oy−Py  Y direction

SPDZ=PZ−OZ  Z direction

[0238] Total number of churning up (set number): Amount=Basic setnumber. Part movement amount.

[0239] Point of origin of churning-up (point of origin of occurrence):FIG. 41 is a diagram represented from the height direction (Y direction)of virtual space. When the checked part is moved in the directionindicated by the arrow, as shown in FIG. 42, the point of origin ofoccurrence of churning-up of water or sand is set as OX, epos, OZ).

[0240] Processing of dispersion of sand (water drops): the X and Zcomponents of the basic speed of the checked part are extracted. FIG. 43is the X-Z plane of virtual model space set up in the image generatingdevice. This Figure shows a condition in which this plane is seen from aposition diagonally above it. The vectors of the X, Z components arerandomly rotated in a range from +135° to −135° in the XZ plane. In theFigure, the range enclosed by the circle (excluding the hatched portion)is the direction in which sand (or water drops) are dispersed.

[0241] Let us now take A as a vector that is randomly rotated. Next,take A′ as being the result obtained by moving L in the direction of thevector along this vector. In this case “L” is the radius of the part.For example, in the case of a leg this is set to 10 cm, in the case ofhips this is set to 20 cm, and in the case of the head this is set to 15cm. The final speed of churning-up of sand and water droplets isdetermined by adding this A′ to the Y component of the basic speed.After this speed has been determined, the sand or water droplets etc.are moved along the track shown in FIG. 40 whilst being subjected topattern change. In this way, as shown in FIG. 44, the appearance of sand(water drops) being scattered in all directions from around the part(radius L) is simulated.

[0242] Next, the processing of occurrence of churning-up will bedescribed. Let us assume that a foot is kicked upwards in water or sandas shown in FIG. 45 corresponding to FIG. 41. In the case of such anaction, let the basic speed of the checked part be (Px-OX, Py-Oy,PZ-OZ). The angle of churning-up of this vector (COS θ), as shown in theFigure, is calculated, as shown in FIG. 46, using the inner product ofthe vector.

[0243] The reason for finding COS θ in this case is that the amount ofchurning-up decreases as the angle of churning-up gets larger, as itgets closer to (90°). That is, the set number for the water/sand is:Basic set number. Amount of movement. COS θ.

[0244] The speed of the sand/water drops is a value obtained bymultiplying the basic speed by the numerical value of a random number(0˜255)/2550. This is identical with the previous case of occurrence onlanding. Variations in sand/water scattering occurring randomly can berepresented by multiplying by a random number. The point of generationof scattering of sand or water is obtained by further adding (OX, Oy,OZ) to this speed. Referring to FIG. 47, if the random number is{fraction (1/10)} (={fraction (255/2550)}), the point of generation isexpressed by the co-ordinates shown in FIG. 47. Sequential patternchange (32 patterns) is applied to the sand/water as shown in FIG. 40.

[0245] Continuation processing, as described above, is used to effectcontinuous display of sand/water scattering, using the landingoccurrence point or churning-up occurrence point that has thus beendetermined.

[0246]FIG. 48 is a flow chart of this embodiment (processing of movementof flying material) described above. In S1600, it is determined whetherthere is a water surface below the checked part or not. Thisdetermination is performed for a stage (scene) in which churning-up ofwater or sand is anticipated. In other words, this determination is notperformed where the surface on which the warrior is standing is a rockysurface, soil, or other solid object. By proceeding in this way,although there are various different stages, such processing of flyingmaterial can be carried out rapidly by being confined to the stageswhere it is necessary. If the surface below the part is not water,processing shifts to the next step. In this stage, the groundingattribute flag described above (b water) is set to “1”. In the case of astage above sand, processing shifts to processing (S1602) of a sandysurface. However, since this processing is identical with the processingon a water surface, description thereof is omitted. In the next process,in S1604, a determination is made as to whether or not any part of thecharacter (warrior) has landed, by comparing the Y co-ordinate (Py) ofthe current position of the character and the Y co-ordinate (epos) ofthe water surface position. Depending on this determination, if thechecked part is below the water surface, processing shifts to processingof occurrence of landing, while, in the opposite case to this, it shiftsto processing of occurrence of churning up.

[0247] In S1606, a determination is made as to whether or not [thecharacter] was in the grounded condition at the previous interrupt, bychecking the landing determination flag. If this flag (b air) is “0”,this grounded condition is continued for a few interrupts (S1608). Onthe other hand, if this flag is “1”, it is concluded that landing hasjust occurred at the present interrupt, and landing occurrenceprocessing (S1610) is performed; also, this flag is reset to “0” (S1612)and return is effected to the main routine of FIG. 34.

[0248] However, if the Y co-ordinate of the checked part is higher thanthe position of the water surface, processing shifts to S1614 and [adetermination] is performed as to whether or not the character was inthe grounded condition on the preceding interrupt, by checking thelanding determination flag. If, on the previous occasion, the characterwas in a landed condition i.e. the checked part was below the watersurface, it is assumed that, for example, kicking-up by the feet asshown in the Figure has currently taken place and the upwardschurning-up pattern is displayed (S1616) matching the movement of thefeet through the water. This flag is then set to “1” and return (S1617)is executed. On the other hand, if the character was not in the landedcondition on the previous occasion, churning-up processing is continued(S1618).

[0249] As described above, with this embodiment, the amount of movementand the direction of movement of a character can be reflected by thesurface material (water or sand etc.) that is moved to match themovement of the character.

[0250] Next, processing will be described that simulates flying-upmovement (one type of flying material movement processing) of leaves(one type of flying material) that has fallen on to the stage caused bya wind generated by movement of a character (warrior) in the game.

[0251] Referring to FIG. 49, 170 indicates a moving warrior and 172indicates leaves that are made to fly up by the moving warrior. “Wind”as referred to herein does not mean a wind that is maintained forseveral interrupts but, rather, a vector that has an effect on thebehaviour of leaves within a single interrupt (an interrupt is theperiod for display of one scene and is in this case {fraction (1/60)}seconds, in other words, the period between vertical synchronisationsignals).

[0252] This processing is executed in accordance with the diagrammaticflowchart shown in FIG. 50. In this flowchart, a check is performed(S1800, S1802) to establish whether or not a wind has been generated bymovement of a character. Next, when generation of a wind is simulated,processing shifts to the routine to check flying-up of leaves (S1804),and the movement of leaves is the simulated (S1806). In this gamesmachine, the condition that leaves that have been initially blown upinto the air are allowed to fall is simulated; this free fallingmovement is continued until the leaves reach the ground surface; afterthe leaves reach the ground surface from the air, movement of the leavesalong the ground until they stop is also simulated. If no wind isgenerated, movement of the leaves is continued (S1806) without checkingwhether the leaves are blown up.

[0253] First of all, a flow chart for checking generation of wind willbe described with reference to FIG. 51. In S1900, the part position iscalculated. This calculation is performed at each interrupt mutually forwarriors 1 and 2, if there are a pair of warriors. The parts that aresubjected to the check are a total of three locations: right leg, leftleg, and head. Whether or not wind is generated is determined bychecking the amounts of movement of these respective parts. Thisdetermination is performed as follows. As shown in the Figure, let ustake the position of the part being checked on the previous occasion(i.e. one interrupt previous) as (OX, Oy, OZ), and the position on thepresent occasion as (PX, Py, PZ). The amount of movement M on thisoccasion is as indicated by equation (1) of FIG. 51. In this case, theamount of movement M′ (expression (2)) in the XZ co-ordinate system isemployed. In step S1902, if M′ is larger than 0.2, the amount ofmovement of the part is deemed to be sufficient to generate wind, andprocessing shifts to the next step. If M′ is smaller than this value,wind is deemed not to be generated and this routine is terminated. InS1904, if the amount of movement (Py−Oy) in the Y direction is (Py−Oy)≦−0.8, the wind direction is deemed to be extremely downwards and windis therefore deemed not to be generated. In Si906, the wind generationflag is set to “wind is generated (=1)”, and the wind generationposition and wind magnitude (vector) are determined.

[0254] The wind generation position and the vector of its X, Y, Zdirection are as shown in the Figure. M′ is corrected to 0.12 ≦ M′ ≦1.0.This M′ is the vector of the Y direction of the wind. The vectors of theX and Z directions are taken to be values obtained by multiplying theamounts of change of the X direction and Y direction by 0.6. The reasonfor multiplying by 0.6 is that the vectors in the X and z directions aretaken to be relatively smaller in value than the vector in the Ydirection, so as chiefly to simulate the condition of wind blowingupwards in model space. Wind is deemed to generate only a single vectorduring a single interrupt. If wind is generated in more than onelocation, wind is deemed to be generated in whichever of these has thelargest value.

[0255] Next, a flow chart of the check for blowing-up of leaves will bedescribed (FIG. 52). A check is made for each leaf, using the windgeneration position and leaf position, to ascertain whether or not theleaf could be affected by wind; if it is within the affected range, themovement of the leaf (speed, vector) is changed under the effect of thewind.

[0256] In step 2000, the wind data and leaf data are read. These data (Xcomponent, Y component and Z component) are as shown in the Figure.Calculation regarding the height of the leaf is performed in S2002. Thiscalculation is as follows. Letting the height from the ground be epos, aheight 1 m above the ground is epos +1.0 (m). Let us take C1 as thevalue obtained by subtracting the height of the leaf 1 ypos from thisheight.

C1=epos+1.0−1 ypos  (m)

[0257] If C1≦0, the position of the leaf (more than 1 m above theground) is deemed to be sufficiently high as not to be effected by thewind produced by actions of the character, so processing is terminated.Under these conditions, the leaf is not effected by wind (degree ofeffect 0%). On the other hand, if it is determined that there will be aneffect due to wind (S2004: No) i.e. if C1>0, the effect coefficientcorresponding to the value of C1 is determined (S2006). For example, ifthe leaf is on the ground, (1 ypos=epos, C1=1) so the leaf undergoes100% of the effect of the wind. If C1=0.5, it undergoes 50% of theeffect. C1 takes a value 0 C1 ≦1.0. This is explained in FIG. 68. Thiseffect coefficient is a coefficient for designating what percentage ofthe effect of the wind the leaf is subjected to, depending on the heightof the leaf. Next, in S2008, the position of generation of the wind andthe distance LI in the XZ plane of the leaf are calculated. As describedabove, w yspd in the calculation expression of L′ shown in the Figure isthe vector in the Y axis direction of the wind and also serves as theeffect distance (radius) with respect to the leaf. If w yspd-L′ is 0 orless, the leaf is deemed to be outside the range of effect of the wind,so there is deemed to be no effect from the wind and return is executed(S2010). On the other hand, if it is more than 0, C2 (effect coefficientdependent on distance) is calculated. Further, this C2 is corrected tocalculate C2′. An example of this effect coefficient is shown in FIG.68. In S2014, the effect of the wind on the leaf (vector: X direction, Ydirection, Z direction) i.e. the speed of the leaf (vector) isdetermined as shown in the Figure; thus the movement of the leaf issimulated (S1806 of FIG. 50) by adding this effect at the currentposition of the leaf. The processing routine for leaf movement will bedescribed immediately afterwards. The leaf speed in the X direction andZ direction are constantly newly set and the Y speed is added to thespeed on the previous occasion (previous interrupt). Next, a detailedflow chart simulating leaf movement is described (FIG. 53). As shown inFIG. 54, two modes of leaf movement, namely, movement of the centreposition of the leaf and rotational movement X, Y rot are given.

[0258] (1) shows movement in which the centre position of the leaf isdisplaced by the effect of wind or by weight and (2) shows flutteringmovement of the leaf simulated by X rot and Y rot. These movements aredescribed by a diagrammatic flow chart and constitute one link ofpre-fall movement.

[0259] A characteristic expression for the former movement (when in theair and when landed from the air) is as shown in S2100 of the Figure.The reason for multiplying the speed in the X direction (1 xspd) by 0.87to obtain the new speed in the X direction in the case where the leaf isin the air is to take into account air resistance. The same applies inregard to the Z direction. The new speed in the Y direction is obtainedby subtracting 0.002 from the speed in the Y direction. This simulatesgradual increase in the speed in the direction of the weight of theleaf. However, the maximum speed of fall in the Y direction (1 yspd) istaken as −0.006. The case where the leaf has landed will be describedlater. In contrast, as shown in FIG. 55, the fluttering condition ofleaf 230 is simulated by means of X rot and Y rot described above. Inthis embodiment, 32 patterns of X rot are provided and successivepattern changing is performed. Rotation based on Y rot is as follows.

Y rotational speed=1 yspd×1200×256

[0260] One-turn rotation (360°) is expressed by 0×0000˜0×FFFF (0˜65536).This is 1° (solid black block symbol)² 182 (0×b6). It should be notedthat, if Y rot were also subjected to pattern changing, there would be arisk of leaf movement simulation appearing to be coarse, so only onerotational element (X rot) is subjected to pattern change, the remainingelement (Y rot) being found by calculation.

[0261] As shown in FIG. 53, movement of the leaf after it has reachedthe ground surface is simulated using the centre movement characteristicexpression and rotational movement characteristic expression (S2100,S2102). The centre movement characteristic expression is shown in FIG.53. In this movement characteristic expression, the speed of the leaf inthe Y axis direction (1 yspd) is set to 0, so a condition in which theleaf moves over the ground surface whilst rotating is simulated. In thischaracteristic expression, the reason why the X direction speed and Ydirection speed are respectively multiplied by 0.5 is to take account ofground friction: the fact that the frictional resistance of the groundis larger than the resistance of the air is simulated by multiplying bya smaller value than in the case where the leaf is in air. Adetermination is made as to whether or not the angle of rotation of theleaf about the X axis (X rot) is “0”; if it is “0”, the leaf is deemedto have come into contact with the ground surface in parallel andmovement of the leaf is stopped. After the leaf has risen into the airunder the influence of the wind generated by movement of the character,movement of the leaf is therefore stopped at the time point when thisleaf falls on to the ground surface and becomes parallel with the groundsurface.

[0262] Whether a leaf that had been floating in the air has landed ornot is determined by comparing the Y co-ordinate of the ground surfaceand the Y co-ordinate of the leaf. If the Y co-ordinate of the leaf s(or “=”) the Y co-ordinate of the ground surface, the leaf is determinedto be in a grounded condition. Shape modelling of the leaf is effectedby mapping a leaf design (texture) on to a single polygon.

[0263] Since the amount of movement and direction of movement of theflying material (water/sand/leaf) as described above is determined bythe movement characteristic of the character (model), the movement ofthe model can be precisely reflected in the flying material. Such flyingmaterial is made to fly up or falls down in response to the movement ofthe original model, so the actions of the flying material can besimulated with high quality by reflecting the movement of the model tothese.

[0264] Also, with the movement processing of moving material describedabove, (free) falling movement of the model (flying material) in virtualspace can be reproduced with a high degree of dramatic effect and withhigh quality. For example, images of fluttering leaves can be generated.

[0265] Free-Fall Movement Processing

[0266] Next, movement processing of an object falling in virtual spacewill be described. In this embodiment, the object is taken to be snow,and simulation of dramatic effects by applying a “swirling” movement tothe snow will be described. In this connection, what is meant by“swirling” is a comparatively irregular movement such as a condition inwhich snow falls whilst being blown about by the wind or a condition inwhich the snow rises and falls in the manner of a falling leaf afterbeing stirred up by movement of a warrior. This embodiment efficientlysimulates this “swirling” condition. A practical example of the swirlingof snow will now be described. The swirling and falling snow isconstituted by one or more polygons and is affected by the wind vectorthat is set up in model space (this vector may be suitably varied). Themovement of the snow polygons is simulated by the effect produced byfree fall due to its weight and the wind vector (the foregoing is thefirst means of the claim) and by circular movement (second means of thesame claim) in the XZ plane of virtual space (horizontal plane i.e.co-ordinate system parallel to the ground surface). The angular speedand amplitude of the circular movement are stored in tabular form in thememory and one of these is selected for use. The circular movementdescribed above that applies swirling to the behaviour of the snow isapplied as follows. Taking the angular speed as wo, the angle ofrotation as q and the amplitude as a, the amount of offset with respectto the X component (x off) and Z component (z off) of the swirlingcomponent i.e. the basic behaviour of the snow (determined by free falland a vector due to the wind) is as follows.

x off=sin (q+ω)·a

y off=cos (q+ω)·a

[0267] This offset data is calculated ten times during each interruptand added to the basic position of the snow. The equation of motion ofthe snow is as follows.

[0268] x pos: snow position (X direction)

[0269] y pos: snow position (Y direction)

[0270] z pos: snow position (Z direction) are assumed.

[0271] x pos=x pos+x off+wind x (x component of wind vector speed)

[0272] y pos=y pos+fall (falling speed of the snow), for example −1cm/int)

[0273] z pos=z pos+z off+wind z (z component of the wind vector speed)

[0274] In the present embodiment, the swirling and falling behaviour ofsnow blown about by the wind (see FIG. 56) is expressed by the foregoingequations of motion. Consequently, the complex “swirling” movement ofthe snow can be obtained by a simple calculation expression and thecalculation load applied to the CPU block is therefore not very great.

[0275]FIG. 56 shows the track of movement of such snow: even though avector whose magnitude and direction are varied in a prescribeddirection is added to freely falling snow, the “swirling” conditioncannot be accurately simulated. Accordingly, this “swirling” may bereproduced by adding a circular motion (this is a type of circulatingmovement; elliptical movement or the like could also be employed) tothis snow.

[0276] By means of this processing, the quality in simulating free-fallmovement of a model in virtual space can be raised, so the dramaticeffect of free-fall image processing can be manifested to a high degree.

[0277] Collision determination processing in irregularly shaped zoneNext, collision processing between an irregularly shaped zone and amodel will be described. This processing has the following significance.In this connection, a zone is a region restricting movement of a warriorand can easily be understood by for example imagining a ring whoseperiphery is enclosed by a wall of irregular shape. The warrior can movefreely within this ring but can not cross the wall to move out side thering. This wall corresponds to a “zone” in this description.

[0278] An irregularly shaped zone 250 is shown at (A) of FIG. 57. Thiszone is set up in the XZ plane (the Y axis is the height direction) ofvirtual space. This zone is set up as a heptagon. Such a zone could beset up in various modes. If a ring with a stone periphery is imagined assuch a zone, this means a stone arena. FIG. 57 shows the principles ofthis processing. The position of the character must be corrected so thatthe character does not move beyond the wall, in order to demonstratethat the wall (zone) actually exists. In this embodiment, collisiondetermination is performed between the character and the wall of thewarrior arena, whose size and shape can be set at will, and an expulsionvector in the normal direction of the wall is calculated in order tocorrect the position.

[0279]FIG. 57 (A) is a model diagram of this collision determination;(B) is a diagram showing the principles of the vector calculation; and(C) is a partial view to a larger scale of the model diagram fordetermination of collision of a character (model) and zone. In FIG. 57,the vector calculation expression is also given. As shown in (A), inthis collision determination, the shape of the character is approximatedby a sphere; furthermore, the wall and this sphere are projected inparallel on to a plane (XZ plane) parallel to the ground surface so asto find the positional relationship between the sides forming the regionof the zone and the circle 252 obtained by projecting the sphere. Theposition of the sphere is the calculated position of the character. Inthis Figure, L is one vertex of an arbitrary side of this zone and R isanother vertex of this side. This is set such that L comes in the anticlockwise direction with respect to an arbitrary side. T in the Figureis the centre-point of the projected circle of the character. Vector R,vector T, and vector L are vectors set from some arbitrary point of thisco-ordinate system to these various points. Also, vector P is a vectordrawn perpendicularly from the centre co-ordinate of the circle to eachside of the zone. Vector P is a vector drawn at right angles to side LRfrom the point of intersection of the circle and the tangent to thiscircle parallel to side LR, and corresponds to the expulsion vector inthis process. The object of this process is the calculation of expulsionvector V. When the centre of the circle is outside straight line RL(this is assumed to be a positive region), as shown in the Figure, anexpulsion vector is set up as shown by expression (1) in the Figure. Incontrast, when the centre of the circle is within straight line RL (thisis taken to be the negative region), it is set up as in expression (2).In other words, if the distance between the centre of the circle andstraight line RL is more than radius (d), an expulsion vector is not setup. If this distance is exceeded, an expulsion vector is set up. In thiscase, since the vector is A directed in the direction of the wall, unitvector Pe is set up in the opposite direction to when the centre of thecircle is outside straight line RL.

[0280]FIG. 58 is a flow chart given in explanation of the operation ofthis embodiment. First of all, the amount of operation of the button ordirection key of the controller is read (S2600). The calculated positionof the character is determined from this operating amount (S2602).Specifically, this position is requested by the operation of thecontroller and is the position of the character calculated as if therewere no zone.

[0281] Next, in S2604, a comparison is made of this character positionand a given side RL. Specifically, the relationship of expression (3) ofFIG. 57 is checked. If the result of this determination is negative(>1), this relationship is checked for the next side RL. If in this casea vector P cannot be drawn at right angles to this side from point T (inother words, this cannot be done in respect of a side that is thesubject of collision determination), processing shifts to S2608 withoutperforming calculation processing of vector P of S2606.

[0282] If this relationship is affirmed, the value of vector P iscalculated in accordance with what is shown in FIG. 57 in S2606. Next,in S2608, a determination is made as to whether the processing of S2604has terminated for all the sides; if this is denied, processing shiftsto S2610 and comparison is executed for the other sides (S2604). On theother hand, if this is affirmed, processing shifts to S2612 and theminimum value of vector P is selected. The side at which this vector Pis to be set up is determined as the wall (side/zone) at which anexpulsion vector is to be set up in the normal direction. In otherwords, it is determined that the character is making contact with theside where this vector is set up.

[0283] In the next step (S2614), a determination is made as to whetheror not the centre of the circle is within the zone: if it is outside thezone, an expulsion vector is set up in accordance with expression (1) ofthe Figure; if it is within the zone, an expulsion vector is set up inaccordance with expression (2). In the case of expression (1) and (2),if the magnitude of vector P is smaller than the radius of the circle, acollision is deemed to have occurred between the character and the walland the expulsion vector described above is set up. By means of thisexpulsion vector, image processing is executed (S2616) whereby furthermovement of the character beyond this zone (wall) is restrained in theactual image.

[0284] Of course, image processing could be executed whereby, by theexpulsion vector from this wall, the model is pulled by vector V definedin the normal direction of the side from the wall. FIG. 57 shows anexample of image processing in these circumstances, reference numeral350 being a warrior while reference numeral 352 is an irregularly shapedwall. The condition is shown (condition (1) in the Figure) in which,even though a warrior 352 tries to move towards the zone in the Figure(left-hand direction in the Figure), this is obstructed by the zone sothat movement is not possible. That is, as shown in (2) of the Figure,while the warrior 350 as a whole is in a condition in which movement isprevented by the zone, right leg 354 (a subsidiary part of thecharacter) can be extended or retracted as shown by the double-headedarrow. The player can thereby be made aware that the model that he iscontrolling is blocked by a zone so that it cannot move further in thisdirection.

[0285] With the processing indicated in this embodiment, an expulsionvector is arranged to be calculated for each side, so, even in the caseof an irregularly shaped zone, determination of collision between thiszone and the character can be carried out in a reliable manner(specifically, collision determination is affirmed when the value of theexpulsion vector is given) and the results of this determination can bereflected in image processing. Compilation of texture series

[0286] Next, a mode of compiling a repeated texture series will bedescribed. FIG. 59 is a diagram given in illustration of this. In thelower section (Bottom), a first texture series is shown; in the middlesection (Top), a second texture series is shown. In the upper section(Together), there is shown a third texture series obtained as a resultof superimposing the first texture series and second texture series.

[0287] The third texture series is a texture series wherein an image(pattern of reflection on sea) which is an image repeated with aprescribed period is formed at a target. The third texture series isconstituted of 30 still pictures 0˜29; these pictures are successivelymapped onto a polygon (i.e. the pictures are mapped onto polygons 0˜29),then further mapped onto numbers 0˜29; by repeating these operations, itis arranged that the picture changes at the joining portions of thesetexture series (for example 28˜2) take place in a naturalistic manner(continuously, in other words, without skipping pictures). By thismeans, an image in which the reflection pattern on the sea surface isrepeated can be compiled.

[0288] Thus the first and second texture series are compiled usingcommercially available application software, as already described. Inthe generation of the texture series, the parameter values are differentfor respective series. However, due to software limitations, the texturegroups of the first region and last region of the texture series aredesigns showing poor linkage, though they are the same in respectiveseries. Specifically, these are for example number 0 and number 29 ofthe first texture series and number 0 and number 59 of the secondtexture series.

[0289] Accordingly, in this processing, a transparency parameter thatsuccessively changes (0˜100%) is applied to the second texture. Thenumerical values above the second texture series are the values relatingto this transparency. 100% indicates a condition in which there is notransparency at all; apart from this, 7% indicates a condition in whichtransparency is more advanced (93% transparency). 0% gives completetransparency. A parameter of 100% is applied to the first texture.

[0290] The third texture series is compiled by successivelysuperimposing the first texture series and the second texture series.Specifically, number 0 of the third texture series is formed bysuperimposing number 0 of the first texture series and number 30 of thesecond texture series, number 1 of the third texture series is formed bysuperimposing number 1 of the first texture series and number 31 of thesecond texture series, number 29 of the third texture series is formedby superimposing number 29 of the first texture series and number 59 ofthe second texture series.

[0291] In this process, when number 0 of the first texture series andnumber 30 of the second texture series are superimposed, since thetransparency of number 30 of the second texture series is 0 (completelynon-transparent condition), number 0 of the first texture series iscompletely hidden by number 30 of the second texture series so the imageof number 0 of the third texture series is equivalent to the image ofnumber 30 of the second texture series. In contrast, when number 29 ofthe first texture series and number 59 of the second texture series aresuperimposed, since the transparency of number 30 of the second textureseries is 97% (practically transparent condition), the image of number29 of the third texture series is practically equivalent to the image ofnumber 29 of the first texture series (in other words, the image ofnumber 59 of the second texture series is practically invisible). Thus,when the second texture series is generated, the method of applying theparameter is such that the picture of number 30 is a picture thatcontinues from the picture number 29 of the first texture series, so,when the third texture series is viewed, a picture can be generatedwhose joining is naturalistic, as described, at the joining section(number 28˜number 2) of the texture series. By assigning parameters tothe respective texture series such that the picture of the end sectionof the first texture series (for example number 25 to 29) and that atthe initial section of the second texture series (for example number 30to number 34) link up (or effectively do so), as shown by the arrow inthe Figure, by taking into account transparency, continuity can beachieved from number 29 of the first texture series to number 30 of thesecond texture series, thereby producing pictures in a naturalisticallylinked mode as illustrated in the drawing by the third texture series.

[0292] By storing the third texture series in a prescribed region ofmemory and successively mapping this onto the polygons indicating thesea surface, images can be displayed in which the pattern and shape ofwhite waves on the sea surface (portions of high brightness on thescreen i.e. portions that are displayed as white in FIG. 27) areperiodically repeated. In the example shown in the Figure, if onepicture is displayed every {fraction (1/30)} sec, taking this as being30 pictures, images in which the pattern of the white-waves portion ofthe sea surface is periodically repeated every second can be reproduced.

[0293] The speed with which the wave mode is reproduced and the numberof textures employed can be altered as required. Taking the case of astage in which a warrior is standing at the centre of the screen, in thenear area of the stage (i.e. the vicinity of the centre of the screen),a reproduction speed of ({fraction (1/30)} sec per frame, 30 framereproduction) as described may be assumed; for waves further than this,in order to reduce the calculation load on the computer, thereproduction speed per frame can be lowered and the total number offrames used can be reduced. For example, frames number 0, number 10,number 20 and number 29 of the third texture series may be employed. Thereason for doing this is because, even though the reproduction of theimages in the vicinity of the periphery of the screen is somewhat rough,the adverse impression on the player is slight and there is more benefitin the lowering of the calculation load on the computer graphics device.

[0294] The third texture series is stored in memory of the games deviceas described. A character series as described above can therefore byutilised in the field of games machines employing computer graphics. Thedescribed method of generating a character series can be used not onlyin the technical field of computer graphics but also in the technicalfield of compilation of animation video. Slow Reproduction Processing

[0295]FIG. 61 to 64 are character operating diagrams given inexplanation of the principles of slow reproduction processing(processing with altered reproduction speed). A condition is shown inwhich two warriors 290 and 292 are facing each other and the twowarriors are competing in order to decide which of the two has superiorskills. In FIG. 61, 290 is the warrior under attack and 292 is theattacking warrior. Reference numeral 294 is the site of an attack wherewarrior 290 has been subjected to an attacking move (attack: punch) fromwarrior 292. FIG. 61 and FIG. 62 which is a plan view of FIG. 61 seenfrom above shows the condition in which warrior 290 has been directlysubjected to the attack.

[0296] In contrast, as shown in FIG. 63 and FIG. 64 which is a plan viewthereof, warrior 290 parries (i.e. defends) the move from warrior 292using his right hand part; if this succeeds, a motion is reproducedwhereby warrior 292 recoils (gets out of position) in the direction ofthe arrow. At this point, slow reproduction is performed whereby thereproduction speed of the motion of warrior 292 is lowered.

[0297] Thus, let us now suppose that one character (warrior) performs amove (“punch”) on another warrior. On the other hand, let us assume thatthe other warrior practically simultaneously performs a move parryingthis punch. It should be noted that this punch or parry could begenerated by suitable operation of a control button and/or direction keyby the player.

[0298] When parrying of this punch is established, a motion is generatedwhereby the attacking warrior recoils considerably to the rear. At thispoint, the speed of reproduction of this motion is made smaller than thespeed of reproduction of the images of the defending warrior. When thishappens, due to this slow reproduction, an “opening” is produced inrespect of the attacking warrior, making it easy for the defendingwarrior to perform an attacking move on the attacking warrior. Oncewarrior 292 has recoiled, he gradually returns to his original stance(before recoil) as in FIG. 65. FIG. 66 is a flow chart showing thisprocessing. At S3400, the defending warrior performs a parry asdescribed. In S3402, a determination is made as to whether the otherside′s attacking move (in the case of the Figure, a “punch”) has metwith a parry (i.e. a collision determination in regard to the hand partof the attacking warrior and a hand part that is under a parry actioncommand). If the result of this determination is negative, return isexecuted without performance of slow reproduction. On the other hand, ifthe result of this determination is affirmative, if the attackingcharacter is not positioned in front of the defending character, returnis executed; if it is in front, processing goes to S3406 (S3404). InS3406, a determination is made as to whether the move is a move that canbe parried or not. For example, if it is a punch, it can be parried; ifit is a kick it cannot be parried. This determination can be achievedmore easily by setting up special flags for each move and checking thecontents of the flag register. If the move is a move that can beparried, the process is terminated; if the move is a move that cannot beparried, processing shifts to S3408. In this step, a number of framesfor which slow reproduction is to be performed is set and this is heldin a timer. In the next step, S3410, the amount that is to be parried bythe move is set (in the example of the Figure, if recoil motion of theattacking warrior is reproduced, the amount of recoil of each part). Thenumber of frames and the amount of parry are calculated in accordancewith prescribed characteristic expressions or may be held in tabularform.

[0299] In S3412, the amount of parry is divided by the set number offrames and a leaf amount (amount of movement and direction of movementin the spatial co-ordinate system) corresponding to one frame iscalculated. Then, in S3414, the speed of reproduction (display speed) ofthe attacking warrior is made for example half that of the defendingwarrior. For example, the reproduction speed of the attacking characteris made {fraction (1/30)} sec, half of {fraction (1/60)} sec. Next, inS3416, the timer value is determined;. if this is “0”, slow reproductionis deemed to have been completed and the reproduction speed of theattacking warrior is returned to the original condition (S3417) andreturn is executed. On the other hand, if it is not “0”, the leaf amountfor one frame is multiplied by the timer value and this is regarded asan amount of movement by the attacker. Then, in S3420, this amount ofmovement is added to the co-ordinate value of the attacking warrior.Specifically, in the position of attacking warrior 292 of FIG. 51, theamount of movement (recoil amount: original position (position ofwarrior 292 of FIG. 61)) when a parry took place in FIG. 63 is added.Next, in S3422, 1 is subtracted from the value (T) of the timer, and, inS3424, the motion position of the attacking warrior 292 (FIG. 63) isre-calculated. Return to the main routine is then executed.

[0300] With this processing, if the parry succeeded, images arereproduced wherein the attacking warrior, after first of all recoilingconsiderably, gradually recoils further in the slow reproductioncondition. At this point, the defending warrior can easily perform anattacking move on the attacking warrior.

[0301] With this processing, reproduction of motion by another warriorcan be performed whilst the reproduction speed f or motion by a firstwarrior is lowered, so the player can more effectively perform fightingmoves of the defending warrior that he is controlling: this has led tothe provision of a facility for slow reproduction as a game element.Slow reproduction can therefore enable a high degree of dramatic effectto be achieved.

[0302] It should be noted that the present invention is not restrictedto the embodiments described above but could be further modified invarious ways by persons skilled in the art within the scope of theclaims.

[0303] As the memory (recording) medium for storing the operatingprogram of the games machine, apart from cartridge ROM or CD-ROM asdescribed above, communication media such as the Internet or personalcomputer networks could be used; an electronic mail server is alsoincluded.

1. A games device wherein image processing is performed such that aprescribed number of models are set up in virtual space and these modelsare controlled such that they move in prescribed directions in thevirtual space and images of this virtual space from a virtual viewpointare displayed by means for display; comprising means for imageprocessing whereby virtual centripetal force is applied to the models.2. An image processing device for games wherein a prescribed number ofmodels are set up in virtual space and these models are controlled suchthat they move in prescribed directions in the virtual space and imagesof this virtual space from a virtual viewpoint are displayed by meansfor display; comprising means for image processing whereby virtualcentripetal force is applied to the models.
 3. An image processingdevice for games wherein a prescribed number of models are set up invirtual space and these models are controlled such that they move inprescribed directions in the virtual space and images of this virtualspace from a virtual viewpoint are displayed by means for display;comprising means for image processing whereby the amount of frictionalforce which is applied to these models is varied when the models aremoving and when they are stationary.
 4. An image processing device forgames wherein a prescribed number of models are set up in virtual spaceand these models are controlled such that they move in prescribeddirections in the virtual space and images of this virtual space from avirtual viewpoint are displayed by means for display; comprising meansfor image processing whereby a projection image of the models isdisplayed matching the surface shape of a stage on which the models areplaced.
 5. An image processing device for games wherein a prescribednumber of models are set up in virtual space and these models arecontrolled such that they move in prescribed directions in the virtualspace and images of this virtual space from a virtual viewpoint aredisplayed by means for display; comprising means for image processingwhereby a determination is performed of overlap of the field of viewcreated by the virtual viewpoint with respect to the model which is thesubject of display and another model which is not set as the subject ofdisplay, and, if the result of this determination is affirmative, theother model is not displayed.
 6. An image processing device for gameswherein a prescribed number of models are set up in virtual space andthese models are controlled such that they move in prescribed directionsin the virtual space and images of this virtual space from a virtualviewpoint are displayed by means for display; comprising means for imageprocessing whereby, with respect to the end-point of a pre-determinedmovement track of the model, a target point is set up different fromthis end-point and the movement track is interpolated such that theend-point coincides with this target point.
 7. An image processingdevice for games wherein a prescribed number of models are set up invirtual space and these models are controlled such that they move inprescribed directions in the virtual space and images of this virtualspace from a virtual viewpoint are displayed by means for display;comprising means for image processing whereby a difference of level atwhich the model is positioned in the virtual space is found and theaction which is applied to this model is interpolated in accordance withthis level difference.
 8. An image processing device for games wherein aprescribed number of models are set up in virtual space and these modelsare controlled such that they move in prescribed directions in thevirtual space and images of this virtual space from a viewpoint at aprescribed position are displayed by means for display; comprising meansfor residual image representation processing for representing the trackof movement of a model as residual images; this means for processingcomprising means for storage whereby motion data of the model before thecurrent motion are stored without modification and means for displaycontrol whereby this stored data is displayed together with currentmotion data of the model.
 9. The image processing device for gamesaccording to claim 8 wherein the means for display control comprisemeans for dramatic effects for effecting display with addition ofdramatic effects to the data of the means for storage.
 10. The imageprocessing device for games according to claim 9 wherein the means fordramatic effects perform semi-transparent image processing.
 11. An imageprocessing device for games wherein a prescribed number of models areset up in virtual space and these models are controlled such that theymove in prescribed directions in the virtual space and images of thisvirtual space from a viewpoint at a prescribed position are displayed bymeans for display; comprising means for dramatic effects that applydramatic effects to the movement characteristic of the model and meansfor controlling flying material that cause flying material to be presentin the virtual space and that control a series of movements of thisflying material in accordance with the results of the calculation by themeans for calculation.
 12. An image processing device for games whereinfree-fall movement of a model set in virtual space is simulated andcomprising first means for simulating overall movement of the model andsecond means for conferring a circulating movement on the model.
 13. Animage processing device for games wherein a prescribed number of modelsare set up in virtual space and these models are controlled such thatthey move in prescribed directions in the virtual space and images ofthis virtual space from a viewpoint at a prescribed position aredisplayed by means for display; comprising means for setting up a zonethat set up an irregularly shaped zone in the virtual space; means forsetting up a vector consisting of means for setting a prescribed vectorbetween this zone and this model and that, if this model tries to movebeyond this zone, sets up this vector in a direction such that the modeldoes not go beyond the zone; and means for controlling model movementthat control the movement of the model in accordance with this vector.14. A texture generating device, in a device in which texture is formedthat varies in periodic fashion on application of a prescribedparameter, comprising first means for creating a first texture seriesand means for creating a second texture series and wherein a textureseries is formed wherein parameters are applied to the respective meanssuch that the last or first texture of the first texture series and thefirst or last texture of the second texture series are constituted incontinuous mode and the degree of transparency of at least one of thefirst texture series and second texture series is gradually increased orgradually decreased with the object that superposition is effected inorder from the first textures of both texture series.
 15. A method offorming texture series wherein periodically changing textures are formedcomprising a first step of creating a first texture series which changesin a prescribed direction and a step of creating a second texture seriesthat likewise changes in a prescribed direction and wherein the last orfirst texture of the first texture series and the first or last textureof the second texture series are made to be constituted in continuousmode and the degree of transparency of at least one of the first textureseries and second texture series is gradually increased or graduallydecreased with the object that superposition is effected in order fromthe first textures of both texture series.
 16. Image processing devicefor games wherein a prescribed number of models are set up in virtualspace and these models are controlled such that they move in prescribeddirections in the virtual space and images of this virtual space from aviewpoint at a prescribed position are displayed by means for display;comprising first means that determines whether or not a prescribedcondition is established between two models; second means for reflectingthe establishment of the condition in the movement of the respectivemodels and third means for, if this condition is established, changingthe reproduction speed of movement of one model with respect to theother model.
 17. A recording medium on which is recorded the imageprocessing program used in a games device that is controlled such that amodel set up in virtual space moves in a prescribed direction in thevirtual space and that performs image processing whereby images of thisvirtual space from a virtual viewpoint are displayed; in which theprogram contains information that sets out a series of procedures toapply virtual centripetal force to the model.